Leetcode 216 Combination Sum III

Leetcode 216 Combination Sum III

class Solution {
public:
vector<vector<int>> combination;
vector<vector<int>> combinationSum3(int k, int n) {
vector<int> result;
helper(1,0,k,n,result);
return combination;
}

void helper(int pos,int curSum,int k,int n,vector<int>& result) {
if (curSum == n && result.size() == k){
combination.push_back(result);
return;
}
if (curSum > n || result.size() > k)
return;

for (int i = pos;i <= 9;++ i) {
curSum += i;
result.push_back(i);
helper(i+1,curSum,k,n,result);
curSum -= i;
result.pop_back();
}
}
};