vector<vector<int> > combinationSum2(vector<int> &num, int target) {
sort(num.begin(), num.end());
vector<vector<int> > result;
vector<int> solution;
combinationHelper(num, solution, result, target, 0);
sort(result.begin(), result.end());
vector<vector<int> >::iterator last = unique(result.begin(), result.end());
result.erase(last, result.end());
return result;
}
void combinationHelper(vector<int> &num, vector<int> &solution, vector<vector<int> > &result, int target, int start) {
for(int i = start; i != num.size(); ++i){
if(target == num[i]){
solution.push_back(num[i]);
result.push_back(solution);
solution.pop_back();
}else if(target > num[i]){
solution.push_back(num[i]);
combinationHelper(num, solution, result, target-num[i], i+1);
solution.pop_back();
}else return;
}
}
void combinationHelper(int& counter, int target, vector<int>& nums) {
if(target < 0) {
return;
}
if(target == 0) {
counter += 1;
}
for(int i = 0; i < nums.size(); i++) {
target -= nums[i];
combinationHelper(counter, target, nums);
target += nums[i];
}
}
int combinationSum4(vector<int>& nums, int target) {
int counter = 0;
combinationHelper(counter, target, nums);
return counter;
}
