Dadas dos strings 
y 
. Encuentre el prefijo común más largo entre ellos después de realizar cero o más operaciones en la string . En cada operación, puede intercambiar dos letras cualesquiera.
Ejemplos :
Input : a = "here", b = "there" Output : 4 The 2nd string can be made "heret" by just swapping characters and thus the longest prefix is of length 4. Input : a = "you", b = "me" Output : 0
Dado que solo podemos realizar intercambios en la string y la longitud del prefijo debe maximizarse. Entonces, la idea es atravesar la string y verificar si la frecuencia del carácter actual en la string es igual o menor que la de la string . En caso afirmativo, avance en la string y, de lo contrario, rompa e imprima la longitud de la parte de la string hasta la que coincide un carácter en la string .
A continuación se muestra la implementación del enfoque anterior:
C++
// C++ program to find the longest
// common prefix between two strings
// after performing swaps on the second string
#include <bits/stdc++.h>
using namespace std;
void LengthLCP(string x, string y)
{
int fr[26]={0};
int a = x.length(); // length of x
int b = y.length(); // length of y
for (int i=0 ;i<b ; i++)
{
// creating frequency array of
// characters of y
fr[y[i] - 97] += 1;
}
// storing the length of
// longest common prefix
int c = 0;
for (int i=0 ;i<a ; i++)
{
// checking if the frequency of the character at
// position i in x in b is greater than zero or not
// if zero we increase the prefix count by 1
if (fr[x[i] - 97] > 0){
c += 1;
fr[x[i] - 97] -= 1;
}
else
break;
}
cout<<(c)<<endl;
}
// Driver Code
int main()
{
string x="here", y = "there";
LengthLCP(x, y);
return 0;
}
//contributed by Arnab Kundu
Java
// Java program to find the longest
// common prefix between two strings
// after performing swaps on the second string
public class GFG {
static void LengthLCP(String x, String y)
{
int fr[]=new int [26];
int a = x.length(); // length of x
int b = y.length(); // length of y
for (int i=0 ;i<b ; i++)
{
// creating frequency array of
// characters of y
fr[y.charAt(i) - 97] += 1;
}
// storing the length of
// longest common prefix
int c = 0;
for (int i=0 ;i<a ; i++)
{
// checking if the frequency of the character at
// position i in x in b is greater than zero or not
// if zero we increase the prefix count by 1
if (fr[x.charAt(i) - 97] > 0){
c += 1;
fr[x.charAt(i) - 97] -= 1;
}
else
break;
}
System.out.println((c)) ;
}
public static void main(String args[])
{
String x="here", y = "there";
LengthLCP(x, y);
}
// This code is contributed by ANKITRAI1
}
Python3
# Python program to find the longest # common prefix between two strings # after performing swaps on the second string def LengthLCP(x, y): fr = [0] * 26 a = len(x) # length of x b = len(y) # length of y for i in range(b): # creating frequency array of # characters of y fr[ord(y[i]) - 97] += 1 # storing the length of # longest common prefix c = 0 for i in range(a): # checking if the frequency of the character at # position i in x in b is greater than zero or not # if zero we increase the prefix count by 1 if (fr[ord(x[i]) - 97] > 0): c += 1 fr[ord(x[i]) - 97] -= 1 else: break print(c) # Driver Code x, y = "here", "there" LengthLCP(x, y)
C#
// C# program to find the longest
// common prefix between two strings
// after performing swaps on the
// second string
using System;
class GFG
{
static void LengthLCP(String x, String y)
{
int []fr = new int [26];
int a = x.Length; // length of x
int b = y.Length; // length of y
for (int i = 0 ; i < b; i++)
{
// creating frequency array
// of characters of y
fr[y[i] - 97] += 1;
}
// storing the length of
// longest common prefix
int c = 0;
for (int i = 0 ; i < a; i++)
{
// checking if the frequency of
// the character at position i
// in x in b is greater than zero
// or not if zero we increase the
// prefix count by 1
if (fr[x[i] - 97] > 0)
{
c += 1;
fr[x[i] - 97] -= 1;
}
else
break;
}
Console.Write((c)) ;
}
// Driver Code
public static void Main()
{
String x = "here", y = "there";
LengthLCP(x, y);
}
}
// This code is contributed by 29AjayKumar
PHP
<?php
// PHP program to find the longest
// common prefix between two strings
// after performing swaps on the second string
function LengthLCP($x, $y)
{
$fr = array_fill(0,26,NULL);
$a = strlen($x); // length of x
$b = strlen($y); // length of y
for ($i = 0 ;$i < $b ; $i++)
{
// creating frequency array of
// characters of y
$fr[ord($y[$i]) - 97] += 1;
}
// storing the length of
// longest common prefix
$c = 0;
for ($i = 0 ;$i < $a ; $i++)
{
// checking if the frequency of the character at
// position i in x in b is greater than zero or not
// if zero we increase the prefix count by 1
if ($fr[ord($x[$i]) - 97] > 0)
{
$c += 1;
$fr[ord($x[$i]) - 97] -= 1;
}
else
break;
}
echo $c;
}
// Driver Code
$x="here";
$y = "there";
LengthLCP($x, $y);
return 0;
// This code is contributed by ChitraNayal
?>
Javascript
<script>
// JavaScript program to find the long
// common prefix between two strings
// after performing swaps on the second string
function LengthLCP(x, y)
{
let fr = Array(26).fill(0);
let a = x.length; // length of x
let b = y.length; // length of y
for (let i=0 ;i<b ; i++)
{
// creating frequency array of
// characters of y
fr[y[i].charCodeAt() - 97] += 1;
}
// storing the length of
// longest common prefix
let c = 0;
for (let i=0 ;i<a ; i++)
{
// checking if the
// frequency of the character at
// position i in x in b is greater
// than zero or not
// if zero we increase the
// prefix count by 1
if (fr[x[i].charCodeAt() - 97] > 0){
c += 1;
fr[x[i].charCodeAt() - 97] -= 1;
}
else
break;
}
document.write((c)) ;
}
// driver code
let x="here", y = "there";
LengthLCP(x, y);
</script>
Producción:
4