題目：

解答：

借用39題的解法，將while改為if做迴圈，並對第一個遞迴式做去重即可。

程式碼：

class Solution {
public:
    void findCompare(vector<int>& candidates, 
                     vector<vector<int>>& result, 
                     vector<int>& tmp,       
                     int sum,
                     int
 
 index,
                     int index2,
                     int len,
                     int target){
        int num = candidates[index];
        if(index == len || num > target - sum)    return;
        int tmpindex = index;
        while(candidates[tmpindex] == candidates[tmpindex+1])   ++tmpindex;
 

        findCompare(candidates, result, tmp, sum, tmpindex + 1, index2, len, target);
        if(num <= target - sum){
            tmp[index2++] = num;
            sum += num;
            if(sum == target){
                vector<int> vec(tmp.begin(), tmp.begin() + index2);
                result.
 
push_back(vec);
            }
            findCompare(candidates, result, tmp, sum, index + 1, index2, len, target);
        }
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
                int len = candidates.size();
        sort(candidates.begin(), candidates.end());
        vector<vector<int>> result;
        vector<int> tmp(1000, 0);
        findCompare(candidates, result, tmp, 0, 0, 0, len, target);
        return result;
    }
};