C++ 代码

class Solution {
public:
    vector<vector<int>> res;
    vector<int> path;
    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
        dfs(candidates, target, 0);
        return res;
    }

    void dfs(vector<int>& nums, int target, int cur){
        //cur表示当前累加和
        if(cur==target){
            res.push_back(path); return;
        }else if(cur>target){
            return;
        }else {
            for(int i=0; i<nums.size(); i++){
                //避免重复，只向后找
                if(!path.empty() && nums[i]<path[path.size()-1])
                    continue;
                cur+=nums[i];
                path.push_back(nums[i]);
                dfs(nums,target,cur);
                cur-=nums[i];
                path.pop_back();
            }
        }
    }
};