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: Accepted)

#include<stdio.h>
#include<string.h>
int main(){
	char a[3001], b[3001];
	scanf("%s", a);
	scanf("%s", b);
	int s1 = strlen(a), s2 = strlen(b), i, j, dp[s1+1][s2+1], count;
	for(i=0;i<=s1;i++){
		for(j=0;j<=s2;j++){
			if(i==0||j==0)
				dp[i][j] = 0;
			else if(a[i-1]==b[j-1])
				dp[i][j] = 1 + dp[i-1][j-1];
			else
				dp[i][j] = dp[i-1][j]>dp[i][j-1]?dp[i-1][j]:dp[i][j-1];
		}
	}
	char s[dp[s1][s2]];
	count = dp[s1][s2];
	
	while(i > 0 && j > 0){
		if(a[i-1]==b[j-1]){
			s[count] = a[i-1];
			count --;
			i --;
			j --;
		}else if(dp[i-1][j]>dp[i][j-1])
			i --;
		else
			j --;
	}
    printf("%s", s);
	return 0;
}