Dado un número y encontrar el primer y último dígito de un número.
Ejemplos:
Input : 12345
Output : First digit: 1
last digit : 5
Input : 98562
Output : First digit: 9
last digit : 2
Para encontrar el último dígito de un número, usamos el operador de módulo % . Cuando módulo dividido por 10 devuelve su último dígito.
Supongamos que si n = 1234
, entonces el último dígito = n % 10 => 4
Encontrar el primer dígito de un número es un poco más costoso que el último dígito. Para encontrar el primer dígito de un número, dividimos el número dado por 10 hasta que el número sea mayor que 10. Al final, nos quedamos con el primer dígito.
Aproximación 1 (Con bucle):
C++
// Program to find first and last
// digits of a number
#include <bits/stdc++.h>
using namespace std;
// Find the first digit
int firstDigit(int n)
{
// Remove last digit from number
// till only one digit is left
while (n >= 10)
n /= 10;
// return the first digit
return n;
}
// Find the last digit
int lastDigit(int n)
{
// return the last digit
return (n % 10);
}
// Driver program
int main()
{
int n = 98562;
cout << firstDigit(n) << " "
<< lastDigit(n) << endl;
return 0;
}
Java
// Java Program to find first and last
// digits of a number
import java.util.*;
import java.lang.*;
public class GfG{
// Find the first digit
public static int firstDigit(int n)
{
// Remove last digit from number
// till only one digit is left
while (n >= 10)
n /= 10;
// return the first digit
return n;
}
// Find the last digit
public static int lastDigit(int n)
{
// return the last digit
return (n % 10);
}
// driver function
public static void main(String argc[])
{
int n = 98562;
System.out.println(firstDigit(n) + " "
+ lastDigit(n));
}
}
// This code is contributed by Sagar Shukla
Python3
# Python3 program to find first and # last digits of a number # Find the first digit def firstDigit(n) : # Remove last digit from number # till only one digit is left while n >= 10: n = n / 10; # return the first digit return int(n) # Find the last digit def lastDigit(n) : # return the last digit return (n % 10) # Driver Code n = 98562; print(firstDigit(n), end = " ") print(lastDigit(n)) # This code is contributed by rishabh_jain
C#
// C# Program to find first and last
// digits of a number
using System;
public class GfG{
// Find the first digit
public static int firstDigit(int n)
{
// Remove last digit from number
// till only one digit is left
while (n >= 10)
n /= 10;
// return the first digit
return n;
}
// Find the last digit
public static int lastDigit(int n)
{
// return the last digit
return (n % 10);
}
// driver function
public static void Main()
{
int n = 98562;
Console.WriteLine(firstDigit(n) + " "
+ lastDigit(n));
}
}
// This code is contributed by vt_m
PHP
<?php
// PHP Program to find first
// and last digits of a number
// Find the first digit
function firstDigit($n)
{
// Remove last digit from number
// till only one digit is left
while ($n >= 10)
$n /= 10;
// return the first digit
return (int)$n;
}
// Find the last digit
function lastDigit($n)
{
// return the last digit
return ((int)$n % 10);
}
// Driver Code
$n = 98562;
echo firstDigit($n) . " " .
lastDigit($n) . "\n";
// This code is contributed
// by Akanksha Rai(Abby_akku)
Javascript
<script>
// javascript Program to find first and last
// digits of a number
// Find the first digit
function firstDigit(n)
{
// Remove last digit from number
// till only one digit is left
while (n >= 10)
n /= 10;
// return the first digit
return Math.floor(n);
}
// Find the last digit
function lastDigit(n)
{
// return the last digit
return Math.floor(n % 10);
}
// Driver code
let n = 98562;
document.write(firstDigit(n) + " "
+ lastDigit(n));
// This code is contributed by sanjoy_62.
</script>
Producción
9 2
Complejidad temporal: O(log 10 n)
Espacio auxiliar: O(1)
Aproximación 2 (Sin bucle)
C++
// Program to find first and last
// digits of a number
#include <bits/stdc++.h>
using namespace std;
// Find the first digit
int firstDigit(int n)
{
// Find total number of digits - 1
int digits = (int)log10(n);
// Find first digit
n = (int)(n / pow(10, digits));
// Return first digit
return n;
}
// Find the last digit
int lastDigit(int n)
{
// return the last digit
return (n % 10);
}
// Driver program
int main()
{
int n = 98562;
cout << firstDigit(n) << " "
<< lastDigit(n) << endl;
return 0;
}
Java
// Java program to find first and
// last digits of a number
import java.math.*;
class GFG {
// Find the first digit
static int firstDigit(int n)
{
// Find total number of digits - 1
int digits = (int)(Math.log10(n));
// Find first digit
n = (int)(n / (int)(Math.pow(10, digits)));
// Return first digit
return n;
}
// Find the last digit
static int lastDigit(int n)
{
// return the last digit
return (n % 10);
}
// Driver program
public static void main(String args[])
{
int n = 98562;
System.out.println(firstDigit(n) +
" " + lastDigit(n));
}
}
// This code is contributed by Nikita Tiwari.
Python3
# Python3 program to find first # and last digits of a number import math # Find the first digit def firstDigit(n) : # Find total number of digits - 1 digits = (int)(math.log10(n)) # Find first digit n = (int)(n / pow(10, digits)) # Return first digit return n; # Find the last digit def lastDigit(n) : # return the last digit return (n % 10) # Driver Code n = 98562; print(firstDigit(n), end = " ") print(lastDigit(n)) # This code is contributed by rishabh_jain
C#
// C# program to find first and
// last digits of a number
using System;
class GFG {
// Find the first digit
static int firstDigit(int n)
{
// Find total number of digits - 1
int digits = (int)(Math.Log10(n));
// Find first digit
n = (int)(n / (int)(Math.Pow(10, digits)));
// Return first digit
return n;
}
// Find the last digit
static int lastDigit(int n)
{
// return the last digit
return (n % 10);
}
// Driver program
public static void Main()
{
int n = 98562;
Console.WriteLine(firstDigit(n) +
" " + lastDigit(n));
}
}
// This code is contributed by vt_m.
PHP
<?php
// Program to find first and last
// digits of a number
// Find the first digit
function firstDigit($n)
{
// Find total number of digits - 1
$digits = (int)log10($n);
// Find first digit
$n = (int)($n / pow(10, $digits));
// Return first digit
return $n;
}
// Find the last digit
function lastDigit($n)
{
// return the last digit
return ($n % 10);
}
// Driver Code
$n = 98562;
echo firstDigit($n) , " ",
lastDigit($n), "\n";
// This code is contributed by ajit
?>
Javascript
<script>
// JavaScript program to find first
// and last digits of a number
// Find the first digit
function firstDigit(n)
{
// Find total number of digits - 1
let digits = Math.floor(Math.log(n)/Math.log(10))
// Find first digit
n = Math.floor(n / Math.pow(10, digits))
// Return first digit
return n;
}
// Find the last digit
function lastDigit(n){
// return the last digit
return (n % 10)
}
// Driver Code
let n = 98562;
document.write(firstDigit(n)," ")
document.write(lastDigit(n),"</br>")
// This code is contributed by shinjanpatra
</script>
Producción
9 2
Tiempo Complejidad: O(1)
Espacio Auxiliar: O(1)
Nota importante: log10() es una función matemática presente en el archivo de encabezado math.h. Devuelve el valor log base 10 del parámetro pasado a la función log10().
Publicación traducida automáticamente
Artículo escrito por Mithun Kumar y traducido por Barcelona Geeks. The original can be accessed here. Licence: CCBY-SA