40. 组合总和 II（算法200题-87）

var combinationSum2 = function (candidates, target) {
    candidates.sort()
    const len = candidates.length
    let list = []
    backtrack([], 0, 0)
    return list
    function backtrack(temp, cur, sum) {
        if (sum > target) return
        if (sum === target) {
            list.push([...temp])
        }
        for (let i = cur; i < len; i++) {
            // 剪枝，后续相同元素不需要排序，避免重复
            if(cur <= i -1 && candidates[i] === candidates[i - 1]) continue
            temp.push(candidates[i])
            sum += candidates[i]
            backtrack(temp, i + 1, sum)
            sum -= candidates[i]
            temp.pop()
        }
    }
};