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:
代码语言：javascript复制Input: k = 3, n = 7
Output: [[1,2,4]]Example 2:
代码语言：javascript复制Input: k = 3, n = 9
Output: [[1,2,6], [1,3,5], [2,3,4]]Solution
代码语言：javascript复制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;
}
};
