Diferencia de dos números grandes

Dados dos números como strings. Los números pueden ser muy grandes (pueden no caber en long long int), la tarea es encontrar la diferencia entre estos dos números.

Ejemplos:  

Input : str1 = "11443333311111111100", 
        str2 =     "1144422222221111"
Output : 11442188888888889989

Input :str1 = "122387876566565674",
       str2 =     "31435454654554"
Output : 122356441111911120

Esto se basa simplemente en las matemáticas escolares. Recorremos ambas strings desde el final, una a una restamos dígitos. 

  1. Invierte ambas cuerdas.
  2. Siga restando dígitos uno por uno desde el índice 0′ (en strings invertidas) hasta el final de una string más pequeña, agregue la diferencia si es positiva al final del resultado. Si la diferencia (diff) es negativa, agregue 10 y realice un seguimiento del acarreo como 1, si es positivo, entonces el acarreo es 0.
  3. Finalmente, invierte el resultado.
     

A continuación se muestra la implementación de la idea anterior: 

C++

// C++ program to find difference of two large numbers.
#include <bits/stdc++.h>
using namespace std;
 
// Returns true if str1 is smaller than str2.
bool isSmaller(string str1, string str2)
{
    // Calculate lengths of both string
    int n1 = str1.length(), n2 = str2.length();
 
    if (n1 < n2)
        return true;
    if (n2 < n1)
        return false;
 
    for (int i = 0; i < n1; i++)
        if (str1[i] < str2[i])
            return true;
        else if (str1[i] > str2[i])
            return false;
 
    return false;
}
 
// Function for find difference of larger numbers
string findDiff(string str1, string str2)
{
    // Before proceeding further, make sure str1
    // is not smaller
    if (isSmaller(str1, str2))
        swap(str1, str2);
 
    // Take an empty string for storing result
    string str = "";
 
    // Calculate length of both string
    int n1 = str1.length(), n2 = str2.length();
 
    // Reverse both of strings
    reverse(str1.begin(), str1.end());
    reverse(str2.begin(), str2.end());
 
    int carry = 0;
 
    // Run loop till small string length
    // and subtract digit of str1 to str2
    for (int i = 0; i < n2; i++) {
        // Do school mathematics, compute difference of
        // current digits
 
        int sub
            = ((str1[i] - '0') - (str2[i] - '0') - carry);
 
        // If subtraction is less than zero
        // we add then we add 10 into sub and
        // take carry as 1 for calculating next step
        if (sub < 0) {
            sub = sub + 10;
            carry = 1;
        }
        else
            carry = 0;
 
        str.push_back(sub + '0');
    }
 
    // subtract remaining digits of larger number
    for (int i = n2; i < n1; i++) {
        int sub = ((str1[i] - '0') - carry);
 
        // if the sub value is -ve, then make it positive
        if (sub < 0) {
            sub = sub + 10;
            carry = 1;
        }
        else
            carry = 0;
 
        str.push_back(sub + '0');
    }
 
    // reverse resultant string
    reverse(str.begin(), str.end());
 
    return str;
}
 
// Driver code
int main()
{
    string str1 = "978";
    string str2 = "12977";
 
    // Function call
    cout << findDiff(str1, str2) << endl;
 
    string s1 = "100";
    string s2 = "1000000";
   
    // Function call
    cout << findDiff(s1, s2);
 
    return 0;
}

Java

// Java program to find difference of two large numbers.
import java.util.*;
 
class GFG {
 
    // Returns true if str1 is smaller than str2.
    static boolean isSmaller(String str1, String str2)
    {
        // Calculate lengths of both string
        int n1 = str1.length(), n2 = str2.length();
        if (n1 < n2)
            return true;
        if (n2 < n1)
            return false;
 
        for (int i = 0; i < n1; i++)
            if (str1.charAt(i) < str2.charAt(i))
                return true;
            else if (str1.charAt(i) > str2.charAt(i))
                return false;
 
        return false;
    }
 
    // Function for find difference of larger numbers
    static String findDiff(String str1, String str2)
    {
        // Before proceeding further, make sure str1
        // is not smaller
        if (isSmaller(str1, str2)) {
            String t = str1;
            str1 = str2;
            str2 = t;
        }
 
        // Take an empty string for storing result
        String str = "";
 
        // Calculate length of both string
        int n1 = str1.length(), n2 = str2.length();
 
        // Reverse both of strings
        str1 = new StringBuilder(str1).reverse().toString();
        str2 = new StringBuilder(str2).reverse().toString();
 
        int carry = 0;
 
        // Run loop till small string length
        // and subtract digit of str1 to str2
        for (int i = 0; i < n2; i++) {
            // Do school mathematics, compute difference of
            // current digits
            int sub
                = ((int)(str1.charAt(i) - '0')
                   - (int)(str2.charAt(i) - '0') - carry);
 
            // If subtraction is less than zero
            // we add then we add 10 into sub and
            // take carry as 1 for calculating next step
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
 
            str += (char)(sub + '0');
        }
 
        // subtract remaining digits of larger number
        for (int i = n2; i < n1; i++) {
            int sub = ((int)(str1.charAt(i) - '0') - carry);
 
            // if the sub value is -ve, then make it
            // positive
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
 
            str += (char)(sub + '0');
        }
 
        // reverse resultant string
        return new StringBuilder(str).reverse().toString();
    }
 
    // Driver code
    public static void main(String[] args)
    {
        String str1 = "978";
        String str2 = "12977";
 
        // Function call
        System.out.println(findDiff(str1, str2));
 
        String s1 = "100";
        String s2 = "1000000";
       
        // Function call
        System.out.println(findDiff(s1, s2));
    }
}
 
// This code is contributed by mits

Python3

# Python 3 program to find difference of two large numbers.
 
# Returns true if str1 is smaller than str2.
 
 
def isSmaller(str1, str2):
 
    # Calculate lengths of both string
    n1 = len(str1)
    n2 = len(str2)
 
    if (n1 < n2):
        return True
    if (n2 < n1):
        return False
 
    for i in range(n1):
        if (str1[i] < str2[i]):
            return True
        elif (str1[i] > str2[i]):
            return False
 
    return False
 
# Function for find difference of larger numbers
 
 
def findDiff(str1, str2):
 
    # Before proceeding further, make sure str1
    # is not smaller
    if (isSmaller(str1, str2)):
        temp = str1
        str1 = str2
        str2 = temp
 
    # Take an empty string for storing result
    str3 = ""
 
    # Calculate length of both string
    n1 = len(str1)
    n2 = len(str2)
 
    # Reverse both of strings
    str1 = str1[::-1]
    str2 = str2[::-1]
 
    carry = 0
 
    # Run loop till small string length
    # and subtract digit of str1 to str2
    for i in range(n2):
 
        # Do school mathematics, compute difference of
        # current digits
 
        sub = ((ord(str1[i])-ord('0'))-(ord(str2[i])-ord('0'))-carry)
 
        # If subtraction is less than zero
        # we add then we add 10 into sub and
        # take carry as 1 for calculating next step
        if (sub < 0):
 
            sub = sub + 10
            carry = 1
 
        else:
            carry = 0
 
        str3 = str3+str(sub)
 
    # subtract remaining digits of larger number
    for i in range(n2, n1):
 
        sub = ((ord(str1[i])-ord('0')) - carry)
 
        # if the sub value is -ve, then make it positive
        if (sub < 0):
 
            sub = sub + 10
            carry = 1
 
        else:
            carry = 0
 
        str3 = str3+str(sub)
 
    # reverse resultant string
    str3 = str3[::-1]
 
    return str3
 
 
# Driver code
if __name__ == "__main__":
    str1 = "978"
    str2 = "12977"
     
    # Function call
    print(findDiff(str1, str2))
 
    s1 = "100"
    s2 = "1000000"
     
    # Function call
    print(findDiff(s1, s2))
 
# This code is contributed by ChitraNayal

C#

// C# program to find difference of two large numbers.
using System;
using System.Collections;
 
class GFG {
 
    // Returns true if str1 is smaller than str2.
    static bool isSmaller(string str1, string str2)
    {
        // Calculate lengths of both string
        int n1 = str1.Length, n2 = str2.Length;
        if (n1 < n2)
            return true;
        if (n2 < n1)
            return false;
 
        for (int i = 0; i < n1; i++)
            if (str1[i] < str2[i])
                return true;
            else if (str1[i] > str2[i])
                return false;
 
        return false;
    }
 
    // Function for find difference of larger numbers
    static string findDiff(string str1, string str2)
    {
        // Before proceeding further, make sure str1
        // is not smaller
        if (isSmaller(str1, str2)) {
            string t = str1;
            str1 = str2;
            str2 = t;
        }
 
        // Take an empty string for storing result
        string str = "";
 
        // Calculate length of both string
        int n1 = str1.Length, n2 = str2.Length;
 
        // Reverse both of strings
        char[] ch1 = str1.ToCharArray();
        Array.Reverse(ch1);
        str1 = new string(ch1);
        char[] ch2 = str2.ToCharArray();
        Array.Reverse(ch2);
        str2 = new string(ch2);
 
        int carry = 0;
 
        // Run loop till small string length
        // and subtract digit of str1 to str2
        for (int i = 0; i < n2; i++) {
            // Do school mathematics, compute difference of
            // current digits
            int sub = ((int)(str1[i] - '0')
                       - (int)(str2[i] - '0') - carry);
 
            // If subtraction is less than zero
            // we add then we add 10 into sub and
            // take carry as 1 for calculating next step
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
 
            str += (char)(sub + '0');
        }
 
        // subtract remaining digits of larger number
        for (int i = n2; i < n1; i++) {
            int sub = ((int)(str1[i] - '0') - carry);
 
            // if the sub value is -ve, then make it
            // positive
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
 
            str += (char)(sub + '0');
        }
 
        // reverse resultant string
        char[] ch3 = str.ToCharArray();
        Array.Reverse(ch3);
        return new string(ch3);
    }
 
    // Driver code
    public static void Main()
    {
        string str1 = "978";
        string str2 = "12977";
 
        // Function call
        Console.WriteLine(findDiff(str1, str2));
 
        string s1 = "100";
        string s2 = "1000000";
       
        // Function call
        Console.WriteLine(findDiff(s1, s2));
    }
}
 
// This code is contributed by mits

PHP

<?php
// PHP program to find difference of two large numbers.
 
// Returns true if str1 is smaller than str2.
function isSmaller($str1, $str2)
{
    // Calculate lengths of both string
    $n1 = strlen($str1);
    $n2 = strlen($str2);
 
    if ($n1 < $n2)
    return true;
    if ($n2 < $n1)
    return false;
 
    for ($i=0; $i<$n1; $i++)
    if ($str1[$i] < $str2[$i])
        return true;
    else if ($str1[$i] > $str2[$i])
        return false;
 
    return false;
}
 
// Function for find difference of larger numbers
function findDiff($str1, $str2)
{
    // Before proceeding further, make sure str1
    // is not smaller
    if (isSmaller($str1, $str2)){
        $t=$str1;
        $str1=$str2;
        $str2=$t;
    }
 
    // Take an empty string for storing result
    $str = "";
 
    // Calculate length of both string
    $n1 = strlen($str1);
    $n2 = strlen($str2);
 
    // Reverse both of strings
    $str1=strrev($str1);
    $str2=strrev($str2);
     
    $carry = 0;
 
    // Run loop till small string length
    // and subtract digit of str1 to str2
    for ($i=0; $i<$n2; $i++)
    {
        // Do school mathematics, compute difference of
        // current digits
         
        $sub=((ord($str1[$i])-ord('0'))-(ord($str2[$i])-ord('0'))-$carry);
         
        // If subtraction is less than zero
        // we add then we add 10 into sub and
        // take carry as 1 for calculating next step
        if ($sub < 0)
        {
            $sub = $sub + 10;
            $carry = 1;
        }
        else
            $carry = 0;
 
        $str.=chr($sub+48);
    }
 
    // subtract remaining digits of larger number
    for ($i=$n2; $i<$n1; $i++)
    {
        $sub = ((ord($str1[$i])-ord('0')) - $carry);
         
        // if the sub value is -ve, then make it positive
        if ($sub < 0)
        {
            $sub = $sub + 10;
            $carry = 1;
        }
        else
            $carry = 0;
             
        $str.=chr($sub+48);
    }
 
    // reverse resultant string
    $str=strrev($str);
 
    return $str;
}
 
// Driver code
 
    $str1 = "978";
    $str2 = "12977";
 
    // Function call
    echo findDiff($str1, $str2)."\n";
     
    $s1 = "100";
    $s2 = "1000000";
 
    // Function call
    echo findDiff($s1,$s2);
     
// This code is contributed by mits
?>

Javascript

<script>
 
// Javascript program to find difference
// of two large numbers.
 
    // Returns true if str1 is smaller than str2.
    function isSmaller(str1,str2)
    {
        // Calculate lengths of both string
        let n1 = str1.length, n2 = str2.length;
        if (n1 < n2)
            return true;
        if (n2 < n1)
            return false;
  
        for (let i = 0; i < n1; i++)
            if (str1[i] < str2[i])
                return true;
            else if (str1[i] > str2[i])
                return false;
  
        return false;
    }
     
     // Function for find difference
     // of larger numbers
    function findDiff(str1,str2)
    {
        // Before proceeding further,
        // make sure str1
        // is not smaller
        if (isSmaller(str1, str2)) {
            let t = str1;
            str1 = str2;
            str2 = t;
        }
  
        // Take an empty string for storing result
        let str = "";
  
        // Calculate length of both string
        let n1 = str1.length, n2 = str2.length;
  
        // Reverse both of strings
        str1 = str1.split("").reverse().join("")
        str2 = str2.split("").reverse().join("")
  
        let carry = 0;
  
        // Run loop till small string length
        // and subtract digit of str1 to str2
        for (let i = 0; i < n2; i++)
        {
            // Do school mathematics,
            // compute difference of
            // current digits
            let sub
                = ((str1[i].charCodeAt(0) -
                '0'.charCodeAt(0))
                   - (str2[i].charCodeAt(0) -
                   '0'.charCodeAt(0)) - carry);
  
            // If subtraction is less than zero
            // we add then we add 10 into sub and
            // take carry as 1 for calculating next step
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
  
            str += String.fromCharCode(sub +
            '0'.charCodeAt(0));
        }
  
        // subtract remaining digits of larger number
        for (let i = n2; i < n1; i++) {
            let sub = ((str1[i].charCodeAt(0) -
            '0'.charCodeAt(0)) - carry);
  
            // if the sub value is -ve, then make it
            // positive
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
  
            str += String.fromCharCode(sub +
            '0'.charCodeAt(0));
        }
  
        // reverse resultant string
        return str.split("").reverse().join("")
    }
     
    // Driver code
     
    let str1 = "978";
    let str2 = "12977";
     
    document.write(findDiff(str1, str2)+"<br>");
      
    let s1 = "100";
    let s2 = "1000000";
    document.write(findDiff(s1, s2)+"<br>");
     
    // This code is contributed by rag2127
 
</script>
Producción

11999
0999900

Complejidad temporal: O(n1 + n2)

Espacio auxiliar: O(max(n1, n2))
Solución optimizada: 
podemos evitar las dos primeras operaciones inversas de strings atravesándolas desde el final. 

A continuación se muestra la solución optimizada. 

C++

// C++ program to find difference of two large numbers.
#include <bits/stdc++.h>
using namespace std;
 
// Returns true if str1 is smaller than str2,
// else false.
bool isSmaller(string str1, string str2)
{
    // Calculate lengths of both string
    int n1 = str1.length(), n2 = str2.length();
 
    if (n1 < n2)
        return true;
    if (n2 < n1)
        return false;
 
    for (int i = 0; i < n1; i++) {
        if (str1[i] < str2[i])
            return true;
        else if (str1[i] > str2[i])
            return false;
    }
    return false;
}
 
// Function for finding difference of larger numbers
string findDiff(string str1, string str2)
{
    // Before proceeding further, make sure str1
    // is not smaller
    if (isSmaller(str1, str2))
        swap(str1, str2);
 
    // Take an empty string for storing result
    string str = "";
 
    // Calculate lengths of both string
    int n1 = str1.length(), n2 = str2.length();
    int diff = n1 - n2;
 
    // Initially take carry zero
    int carry = 0;
 
    // Traverse from end of both strings
    for (int i = n2 - 1; i >= 0; i--) {
        // Do school mathematics, compute difference of
        // current digits and carry
        int sub = ((str1[i + diff] - '0') - (str2[i] - '0')
                   - carry);
        if (sub < 0) {
            sub = sub + 10;
            carry = 1;
        }
        else
            carry = 0;
 
        str.push_back(sub + '0');
    }
 
    // subtract remaining digits of str1[]
    for (int i = n1 - n2 - 1; i >= 0; i--) {
        if (str1[i] == '0' && carry) {
            str.push_back('9');
            continue;
        }
        int sub = ((str1[i] - '0') - carry);
        if (i > 0 || sub > 0) // remove preceding 0's
            str.push_back(sub + '0');
        carry = 0;
    }
 
    // reverse resultant string
    reverse(str.begin(), str.end());
 
    return str;
}
 
// Driver code
int main()
{
    string str1 = "88";
    string str2 = "1079";
   
    // Function call
    cout << findDiff(str1, str2);
    return 0;
}

Java

// Java program to find difference of two large numbers.
 
class GFG {
 
    // Returns true if str1 is smaller than str2,
    // else false.
    static boolean isSmaller(String str1, String str2)
    {
        // Calculate lengths of both string
        int n1 = str1.length(), n2 = str2.length();
 
        if (n1 < n2)
            return true;
        if (n2 < n1)
            return false;
 
        for (int i = 0; i < n1; i++) {
            if (str1.charAt(i) < str2.charAt(i))
                return true;
            else if (str1.charAt(i) > str2.charAt(i))
                return false;
        }
        return false;
    }
 
    // Function for finding difference of larger numbers
    static String findDiff(String str1, String str2)
    {
        // Before proceeding further, make sure str1
        // is not smaller
        if (isSmaller(str1, str2)) {
            String t = str1;
            str1 = str2;
            str2 = t;
        }
 
        // Take an empty string for storing result
        String str = "";
 
        // Calculate lengths of both string
        int n1 = str1.length(), n2 = str2.length();
        int diff = n1 - n2;
 
        // Initially take carry zero
        int carry = 0;
 
        // Traverse from end of both strings
        for (int i = n2 - 1; i >= 0; i--) {
            // Do school mathematics, compute difference of
            // current digits and carry
            int sub
                = (((int)str1.charAt(i + diff) - (int)'0')
                   - ((int)str2.charAt(i) - (int)'0')
                   - carry);
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
 
            str += String.valueOf(sub);
        }
 
        // subtract remaining digits of str1[]
        for (int i = n1 - n2 - 1; i >= 0; i--) {
            if (str1.charAt(i) == '0' && carry > 0) {
                str += "9";
                continue;
            }
            int sub = (((int)str1.charAt(i) - (int)'0')
                       - carry);
            if (i > 0 || sub > 0) // remove preceding 0's
                str += String.valueOf(sub);
            carry = 0;
        }
 
        // reverse resultant string
        return new StringBuilder(str).reverse().toString();
    }
 
    // Driver code
    public static void main(String[] args)
    {
        String str1 = "88";
        String str2 = "1079";
       
        // Function call
        System.out.println(findDiff(str1, str2));
    }
}
 
// This code is contributed by mits

Python3

# Python3 program to find difference
# of two large numbers.
 
# Returns true if str1 is smaller than
# str2, else false.
def isSmaller(str1, str2):
     
    # Calculate lengths of both string
    n1 = len(str1)
    n2 = len(str2)
 
    if (n1 < n2):
        return True
    if (n2 < n1):
        return False
 
    for i in range(n1):
        if (str1[i] < str2[i]):
            return True
        elif (str1[i] > str2[i]):
            return False
             
    return False
 
# Function for finding difference
# of larger numbers
def findDiff(str1, str2):
     
    # Before proceeding further,
    # make sure str1 is not smaller
    if (isSmaller(str1, str2)):
        str1, str2 = str2, str1
 
    # Take an empty string for
    # storing result
    Str = ""
     
    # Calculate lengths of both string
    n1 = len(str1)
    n2 = len(str2)
    diff = n1 - n2
     
    # Initially take carry zero
    carry = 0
     
    # Traverse from end of both strings
    for i in range(n2 - 1, -1, -1):
         
        # Do school mathematics, compute
        # difference of current digits
        # and carry
        sub = ((ord(str1[i + diff]) - ord('0')) -
               (ord(str2[i]) - ord('0')) - carry)
 
        if (sub < 0):
            sub += 10
            carry = 1
        else:
            carry = 0
 
        Str += chr(sub + ord('0'))
     
    # Subtract remaining digits of str1[]
    for i in range(n1 - n2 - 1, -1, -1):
        if (str1[i] == '0' and carry):
            Str += '9'
            continue
             
        sub = (ord(str1[i]) - ord('0')) - carry
         
        # Remove preceding 0's
        if (i > 0 or sub > 0):
            Str += chr(sub + ord('0'))
             
        carry = 0
 
    # Reverse resultant string
    Str = Str[::-1]
     
    return Str
 
# Driver code
str1 = "88"
str2 = "1079"
 
# Function call
print(findDiff(str1, str2))
 
# This code is contributed by avanitrachhadiya2155

C#

// C# program to find difference of
// two large numbers.
using System;
 
class GFG {
 
    // Returns true if str1 is smaller
    // than str2, else false.
    static bool isSmaller(string str1, string str2)
    {
        // Calculate lengths of both string
        int n1 = str1.Length, n2 = str2.Length;
 
        if (n1 < n2)
            return true;
        if (n2 < n1)
            return false;
 
        for (int i = 0; i < n1; i++) {
            if (str1[i] < str2[i])
                return true;
            else if (str1[i] > str2[i])
                return false;
        }
        return false;
    }
 
    // Function for finding difference of
    // larger numbers
    static string findDiff(string str1, string str2)
    {
        // Before proceeding further,
        // make sure str1 is not smaller
        if (isSmaller(str1, str2)) {
            string t = str1;
            str1 = str2;
            str2 = t;
        }
 
        // Take an empty string for
        // storing result
        String str = "";
 
        // Calculate lengths of both string
        int n1 = str1.Length, n2 = str2.Length;
        int diff = n1 - n2;
 
        // Initially take carry zero
        int carry = 0;
 
        // Traverse from end of both strings
        for (int i = n2 - 1; i >= 0; i--) {
            // Do school mathematics, compute
            // difference of current digits and carry
            int sub = (((int)str1[i + diff] - (int)'0')
                       - ((int)str2[i] - (int)'0') - carry);
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
 
            str += sub.ToString();
        }
 
        // subtract remaining digits of str1[]
        for (int i = n1 - n2 - 1; i >= 0; i--) {
            if (str1[i] == '0' && carry > 0) {
                str += "9";
                continue;
            }
            int sub = (((int)str1[i] - (int)'0') - carry);
            if (i > 0 || sub > 0) // remove preceding 0's
                str += sub.ToString();
            carry = 0;
        }
 
        // reverse resultant string
        char[] aa = str.ToCharArray();
        Array.Reverse(aa);
        return new string(aa);
    }
 
    // Driver code
    public static void Main()
    {
        String str1 = "88";
        String str2 = "1079";
 
        // Function call
        Console.WriteLine(findDiff(str1, str2));
    }
}
 
// This code is contributed by mits

PHP

<?php
// PHP program to find difference of two
// large numbers.
 
// Returns true if str1 is smaller than
// str2, else false.
function isSmaller($str1, $str2)
{
    // Calculate lengths of both string
    $n1 = strlen($str1);
    $n2 = strlen($str2);
 
    if ($n1 < $n2)
        return true;
    if ($n2 < $n1)
        return false;
 
    for ($i = 0; $i < $n1; $i++)
    {
        if ($str1[$i] < $str2[$i])
            return true;
        else if ($str1[$i] > $str2[$i])
            return false;
    }
    return false;
}
 
// Function for finding difference
// of larger numbers
function findDiff($str1, $str2)
{
    // Before proceeding further, make
    // sure str1 is not smaller
    if (isSmaller($str1, $str2))
    {
        $t = $str1;
        $str1 = $str2;
        $str2 = $t;
    }
 
    // Take an empty string for storing result
    $str = "";
 
    // Calculate lengths of both string
    $n1 = strlen($str1);
    $n2 = strlen($str2);
    $diff = $n1 - $n2;
 
    // Initially take carry zero
    $carry = 0;
 
    // Traverse from end of both strings
    for ($i = $n2 - 1; $i >= 0; $i--)
    {
        // Do school mathematics, compute
        // difference of current digits and carry
        $sub = ((ord($str1[$i + $diff]) - ord('0')) -
                (ord($str2[$i]) - ord('0')) - $carry);
        if ($sub < 0)
        {
            $sub = $sub + 10;
            $carry = 1;
        }
        else
            $carry = 0;
 
        $str.=chr($sub + ord("0"));
    }
 
    // subtract remaining digits of str1[]
    for ($i = $n1 - $n2 - 1; $i >= 0; $i--)
    {
        if ($str1[$i] == '0' && $carry > 0)
        {
            $str.="9";
            continue;
        }
        $sub = (ord($str1[$i]) - ord('0') - $carry);
        if ($i > 0 || $sub > 0) // remove preceding 0's
            $str.=chr($sub + ord("0"));
        $carry = 0;
 
    }
 
    // reverse resultant string
    return strrev($str);
 
}
 
// Driver code
$str1 = "88";
$str2 = "1079";
 
// Function call
print(findDiff($str1, $str2));
 
// This code is contributed by chandan_jnu
?>

Javascript

<script>
 
    // JavaScript program to find difference
    // of two large numbers.
     
    // Returns true if str1 is smaller
    // than str2, else false.
    function isSmaller(str1, str2)
    {
        // Calculate lengths of both string
        let n1 = str1.length, n2 = str2.length;
  
        if (n1 < n2)
            return true;
        if (n2 < n1)
            return false;
  
        for (let i = 0; i < n1; i++) {
            if (str1[i].charCodeAt() < str2[i].charCodeAt())
                return true;
            else if (str1[i].charCodeAt() > str2[i].charCodeAt())
                return false;
        }
        return false;
    }
  
    // Function for finding difference of
    // larger numbers
    function findDiff(str1, str2)
    {
        // Before proceeding further,
        // make sure str1 is not smaller
        if (isSmaller(str1, str2)) {
            let t = str1;
            str1 = str2;
            str2 = t;
        }
  
        // Take an empty string for
        // storing result
        let str = "";
  
        // Calculate lengths of both string
        let n1 = str1.length, n2 = str2.length;
        let diff = n1 - n2;
  
        // Initially take carry zero
        let carry = 0;
  
        // Traverse from end of both strings
        for (let i = n2 - 1; i >= 0; i--) {
            // Do school mathematics, compute
            // difference of current digits and carry
            let sub = ((str1[i + diff].charCodeAt() -
                       '0'.charCodeAt())
                   - (str2[i].charCodeAt() -
                     '0'.charCodeAt()) - carry);
            if (sub < 0) {
                sub = sub + 10;
                carry = 1;
            }
            else
                carry = 0;
  
            str += sub.toString();
        }
  
        // subtract remaining digits of str1[]
        for (let i = n1 - n2 - 1; i >= 0; i--) {
            if (str1[i] == '0' && carry > 0) {
                str += "9";
                continue;
            }
            let sub = ((str1[i].charCodeAt() -
                       '0'.charCodeAt()) - carry);
            if (i > 0 || sub > 0) // remove preceding 0's
                str += sub.toString();
            carry = 0;
        }
  
        // reverse resultant string
        let aa = str.split('');
        aa.reverse();
        return aa.join("");
    }
     
    let str1 = "88";
    let str2 = "1079";
 
    // Function call
    document.write(findDiff(str1, str2));
     
</script>
Producción

991

Complejidad del tiempo : O(n1 + n2)

Espacio auxiliar: O(max(n1, n2))

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Artículo escrito por GeeksforGeeks-1 y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA

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