题目

word-search-ii

算法

* 直接模拟

代码

class Solution {

public:

    vector<vector<int> > combinationSum3(int k, int n) {

        vector<vector<int> > res;

        vector<int> out;

        combinationSum3DFS(k, n, 1, out, res);

        return res;

    }

    void combinationSum3DFS(int k, int n, int level, vector<int> &out, vector<vector<int> > &res) {

        if (n < 0) return;

        if (n == 0 && out.size() == k) res.push_back(out);

        for (int i = level; i <= 9; ++i) {

            out.push_back(i);

            combinationSum3DFS(k, n - i, i + 1, out, res);

            out.pop_back();

        }

    }

};