Function numDecodings

javascript/0091-decode-ways.js:9–19

(str, index = 0, memo = new Map())

 * @return {number}
 */
var numDecodings = (str, index = 0, memo = new Map()) => {
    const isBaseCase1 = !str.length || str[index] === '0';
    if (isBaseCase1) return 0;

    const isisBaseCase2 = index === str.length;
    if (isisBaseCase2) return 1;

    if (memo.has(index)) return memo.get(index);

    return dfs(str, index, memo);
};

const dfs = (str, index, memo) => {
    let count = numDecodings(str, index + 1, memo);