Problem:
Score : 100 points

Problem Statement

You are given strings s and t.
Find one longest string that is a subsequence of both s and t.

Notes

A subsequence of a string x is the string obtained by removing zero or more characters from x and concatenating the remaining characters without changing the order.

Constraints

s and t are strings consisting of lowercase English letters.

1 \leq |s|, |t| \leq 3000

Input

Input is given from Standard Input in the following format:

s
t

Output

Print one longest string that is a subsequence of both s and t.
If there are multiple such strings, any of them will be accepted.

Sample Input 1

axyb
abyxb

Sample Output 1

axb

The answer is axb or ayb; either will be accepted.

Sample Input 2

aa
xayaz

Sample Output 2

aa

Sample Input 3

a
z

Sample Output 3

The answer is (an empty string).

Sample Input 4

abracadabra
avadakedavra

Sample Output 4

aaadara

Solution in C++ (GCC 9.2.1) (judge verdict: Runtime Error)




#include <bits/stdc++.h>
using namespace std;
#define ll long long 
#define inf 1e9+1
string lcs(string s1,string s2){

    int n=s1.length();
    int m=s2.length();

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


    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            
            if(s1[i-1]==s2[j-1]){
                dp[i][j]=1+dp[i-1][j-1];

            }else{
                dp[i][j]=max(dp[i-1][j],dp[i][j-1]);
            }
        }
    }


    int i=n,j=m;

    string ans="";

    while(i>=0 && j>=0){

        if(s1[i-1]==s2[j-1]){
            ans+=s1[i-1];
            i--;
            j--;
            
        }else{
            if(dp[i-1][j]>dp[i][j-1]){
                i--;

            }else{
                j--;

            }
        }

    }

    reverse(ans.begin(),ans.end());


    return ans;


    

}

int main() {
    string s1,s2;
    cin>>s1>>s2;

    cout<<lcs(s1,s2);




}