/**
 * https://leetcode.com/problems/combination-sum-ii/
 * Time O(2^N) | Space O(N)
 * @param {number[]} candidates
 * @param {number} target
 * @return {number[][]}
 */
var combinationSum2 = function (candidates, target) {
    candidates.sort((a, b) => a - b);

    return dfs(candidates, target);
};

const dfs = (
    candidates,
    target,
    index = 0,
    combination = [],
    combinations = [],
) => {
    const isBaseCase = target < 0;
    if (isBaseCase) return combinations;

    const isTarget = target === 0;
    if (isTarget) {
        if (combination.length) combinations.push(combination.slice());

        return combinations;
    }

    for (let i = index; i < candidates.length; i++) {
        const isDuplicate = index < i && candidates[i - 1] === candidates[i];
        if (isDuplicate) continue;

        backTrack(candidates, target, i, combination, combinations);
    }

    return combinations;
};

const backTrack = (candidates, target, i, combination, combinations) => {
    combination.push(candidates[i]);
    dfs(candidates, target - candidates[i], i + 1, combination, combinations);
    combination.pop();
};