34_LCS (Longest Common Subsequence)

const LCS = function (str1, str2) {
    const N = str1.length;
    const M = str2.length;
    const d = Array.from(Array(N+3), () => Array(M+3).fill(0));
  
    for (let i = 1; i <= N; i++) {
      for (let j = 1; j <= M; j++) {
        if(str1[i-1] === str2[j-1]) d[i][j] = d[i-1][j-1]+1;
        else d[i][j] = Math.max(d[i-1][j], d[i][j-1]);
      }
    }
    return d[N][M];
  }