Combination Sum

DFS: almost the same, except the change of depth

I:

class Solution {
public:
    void dfs(vector<int> &num, int target, int start, vector<int> &cur, vector<vector<int> > &res) {
        if (start>num.size()-1) return;
        for (int i=start; i<num.size(); i++) {
            int next_target=target-num[i];
            if (next_target==0) {
                cur.push_back(num[i]);
                res.push_back(cur);
                cur.pop_back();
                return;
            }
            if (next_target>0) {
                cur.push_back(num[i]);
                dfs(num, next_target,i, cur, res);
                cur.pop_back();
            }
        }
    }
    vector<vector<int> > combinationSum(vector<int> &candidates, int target) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        vector<vector<int> > res;
        if (candidates.size()==0) return res;
        vector<int> cur;
        sort(candidates.begin(), candidates.end());
        dfs(candidates, target, 0, cur, res);
        return res;
    }
};

II:

Terminal condition: depth==num. size ()

Depth in next round = i+1 (! = depth + 1)

class Solution {
public:
    void dfs(vector<int> &num, int target, int start, vector<int> &cur, vector<vector<int> > &res) {
        if (start>num.size()-1) return;
        int temp=-1;
        for (int i=start; i<num.size(); i++) {
            if (temp==num[i]) continue;
            temp=num[i];
            int next_target=target-temp;
            if (next_target==0) {
                cur.push_back(temp);
                res.push_back(cur);
                cur.pop_back();
                return;
            }
            if (next_target>0) {
                cur.push_back(temp);
                dfs(num, next_target,i+1, cur, res);
                cur.pop_back();
            }
        }
    }
    vector<vector<int> > combinationSum2(vector<int> &num, int target) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        vector<vector<int> > res;
        if (num.size()==0) return res;
        vector<int> cur;
        sort(num.begin(), num.end());
        dfs(num, target, 0, cur, res);
        return res;
    }
};