Function isInterleave

javascript/0097-interleaving-string.js:10–18

(s1, s2, s3, i = 0, j = 0, res = '')

 * @return {boolean}
 */
var isInterleave = (s1, s2, s3, i = 0, j = 0, res = '') => {
    const isBaseCase1 = s3.length !== s1.length + s2.length;
    if (isBaseCase1) return false;

    const isBaseCase2 = res === s3 && i == s1.length && j == s2.length;
    if (isBaseCase2) return true;

    return dfs(s1, s2, s3, i, j, res); /* Time O(2^(N + M)) | Space O(N + M) */
};

var dfs = (s1, s2, s3, i, j, res, ans = false) => {
    const hasLeft = i < s1.length;