Function bfs

javascript/0046-permutations.js:40–60

(nums, levels = [[]], permutations = [])

};

const bfs = (nums, levels = [[]], permutations = []) => {
    for (const num of nums) {
        for (let i = levels.length - 1; 0 <= i; i--) {
            const previousLevel = levels.shift();

            for (let index = 0; index < previousLevel.length + 1; index++) {
                const level = reArrangeSet(previousLevel, num, index);

                const isBaseCase = level.length === nums.length;
                if (isBaseCase) {
                    permutations.push(level);
                    continue;
                }

                levels.push(level);
            }
        }
    }

    return permutations;
};

const reArrangeSet = (previousLevel, num, index) => {
    const [before, after] = [