Function backtrack

javascript/0473-matchsticks-to-square.js:28–45

(i)

    matchsticks = matchsticks.sort((a, b) => b - a);

    function backtrack(i) {
        if (ans) return;
        if (i >= matchsticks.length) {
            if (check(sides)) {
                ans = true;
            }
            return;
        }
        for (let j = 0; j < 4; j++) {
            if (sides[j] + matchsticks[i] > max_size) {
                continue;
            }
            sides[j] += matchsticks[i];

            backtrack(i + 1);
            sides[j] -= matchsticks[i];
        }
    }
    backtrack(0);

    return ans;