LCS.cpp

#include<bits/stdc++.h>
using namespace std;

int max(int a, int b){
    if(a>b) return a;
    else return b;
}
void lcs(char *X, char *Y, int m, int n){
    int L[m+1][n+1];

    for (int i=0; i<=m; i++){
        for (int j=0; j<=n; j++){
            if (i == 0 || j == 0)
                L[i][j] = 0;
            else if (X[i-1] == Y[j-1])
                L[i][j] = L[i-1][j-1] + 1;
            else
                L[i][j] = max(L[i-1][j], L[i][j-1]);
        }
    }
    int index = L[m][n];
    char lcs[index+1];
    lcs[index] = '\0';

    int i = m, j = n;
    while (i > 0 && j > 0){
        if (X[i-1] == Y[j-1]){
            lcs[index-1] = X[i-1];
            i--;
            j--;
            index--;
        }else if (L[i-1][j] > L[i][j-1])
            i--;
        else
            j--;
    }
    cout << lcs << endl;
    //cout << strlen(lcs);
    //cout << endl;
}
int main(){
    char X[20], Y[20];
    //cout << "LCS" << endl;
    //cout << endl << "Enter 1st Sequence: ";
    cin >> X;

    //cout << "Enter 2nd Sequence: ";
    cin >> Y;
    int m = strlen(X);
    int n = strlen(Y);
    lcs(X, Y, m, n);
    return 0;
}