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 JavaScript (node.js v5.12) (judge verdict: Accepted)

function main(input){
  const lines = input.split('\n');
  const S = lines.shift().split('');
  const T = lines.shift().split('');

  dp = []
  for(var i=0;i<=S.length;i++){
    dp.push( Array(T.length+1).fill(0) );
  }

  for(var i=1;i<=S.length;i++){
    for(var j=1;j<=T.length;j++){
      if(S[i-1]==T[j-1]){
        dp[i][j]=Math.max(dp[i][j], dp[i-1][j-1]+1);
      }else{
        dp[i][j]=Math.max(dp[i-1][j], dp[i][j-1]);
      }
    }
  }

  var i = S.length;
  var j = T.length;
  var result = [];
  while(i!=0 &&  j!=0){
    if(S[i-1]==T[j-1]){
      result.unshift(S[i-1]);
      i--;
      j--;
    }else{
      if(dp[i-1][j] < dp[i][j-1]){
        j--;
      }else{
        i--;
      }
    }
  }

  console.log(result.join(''));
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));