Function dfs

javascript/0115-distinct-subsequences.js:35–58

(s, t, i, j, memo)

    new Array(s.length).fill().map(() => new Array(t.length).fill(null));

var dfs = (s, t, i, j, memo) => {
    const left = numDistinct(
        s,
        t,
        i + 1,
        j,
        memo,
    ); /* Time O(N * M) | Space O(HEIGHT) */

    const isEqual = s[i] === t[j];

    const right = isEqual
        ? numDistinct(
              s,
              t,
              i + 1,
              j + 1,
              memo,
          ) /* Time O(N * M) | Space O(HEIGHT) */
        : 0;

    memo[i][j] = left + right; /*               | Space O(N * M) */
    return memo[i][j];
};

/**
 * DP - Bottom Up