#include <iostream>

#include <string>

#include <vector>

#include <algorithm>




using namespace std;




// Function to find the Longest Common Substring

string LCS(string X, string Y) {

// Find lengths of given strings

int m = X.length();

int n = Y.length();




// Declare the 2D array to store lengths of longest common suffixes

vector<vector<int>> L(m + 1, vector<int>(n + 1, 0));




// Variable to keep track of the maximum length of LCS

int maxLength = 0;

int endIdx = 0; // To store the end index of the longest common substring in X




// Fill the array with values

for (int i = 1; i <= m; i++) {

for (int j = 1; j <= n; j++) {

if (X[i - 1] == Y[j - 1]) {

Lj = L[i - 1][j - 1] + 1;




// Update maxLength if a longer common substring is found

if (Lj > maxLength) {

maxLength = Lj;

endIdx = i - 1;

}

} else {

Lj = 0;

}

}

}




// If there is no common substring, return an empty string

if (maxLength == 0) {

return "";

}




// Extract the longest common substring

return X.substr(endIdx - maxLength + 1, maxLength);

}




int main() {

string X = "ABABC";

string Y = "BABC";




cout << "Longest Common Substring: " << LCS(X, Y) << endl;




return 0;

}

Initialization ofL : Used a vector of vectors to declare a 2D array with zero-initialized values ​​to store lengths of common substrings at each point.Array Access Errors : Fixed the syntax and index accesses, ensuring Ljit was updated correctly.Tracking Max Length and End Index : Added variables maxLengthand endIdxto keep track of the longest common substring's length and where it ends.Return Statement : Used substrto return the longest substring based on the endIdxand maxLength.