LeetCode 0216 - Combination Sum III

Reck Zhang

发布于 2021-08-11 12:12:13

1280

发布于 2021-08-11 12:12:13

文章被收录于专栏：Reck Zhang

Combination Sum III

Desicription

Find all possible combinations of k numbers that add up to a number n, given that only numbers from 1 to 9 can be used and each combination should be a unique set of numbers.

Note:

All numbers will be positive integers.
The solution set must not contain duplicate combinations.

Example 1:

Input: k = 3, n = 7
Output: [[1,2,4]]

Example 2:

Input: k = 3, n = 9
Output: [[1,2,6], [1,3,5], [2,3,4]]

Solution

class Solution {
private:
    vector<vector<int>> res;
    void dfs(vector<int>& current_vector, int current_sum, int current_number, const int k, const int n) {
        for(int i = current_number + 1; i <= 9; i++) {
            if(current_vector.size() == k - 1 && current_sum + i == n) {
                current_vector.push_back(i);
                res.push_back(current_vector);
                current_vector.pop_back();
                return ;
            }
            else if(current_vector.size() < k - 1 && current_sum + i < n) {
                current_vector.push_back(i);
                dfs(current_vector, current_sum + i, i, k, n);
                current_vector.pop_back();
            }
        }
    }
public:
    vector<vector<int>> combinationSum3(int k, int n) {
        vector<int> tmp{};
        dfs(tmp, 0, 0, k, n);
        return res;
    }
};

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原始发表：2018-06-29，如有侵权请联系 cloudcommunity@tencent.com 删除

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