/**
* @param num: Given the candidate numbers
* @param target: Given the target number
* @return: All the combinations that sum to target
*/
vector<vector<int>> combinationSum2(vector<int> &num, int target) {
sort(num.begin(), num.end());
vector<vector<int>> ans;
vector<int> v;
combinationSum2Helper(num, target, 0, v, ans);
return ans;
}
vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
sort(candidates.begin(), candidates.end());
vector<vector<int>> res;
vector<int> comb;
combinationSum2Helper(candidates, target, res, comb, 0);
return res;
}
void combinationSum2Helper(vector<int>& candidates, int target, vector<vector<int>>& res, vector<int>& comb, int begin) {
if(target == 0) {
res.push_back(comb);
}
for(int i = begin; i < candidates.size() && target >= candidates[i]; i++) {
if(i > begin && candidates[i] == candidates[i-1]) {
continue;
}
comb.push_back(candidates[i]);
combinationSum2Helper(candidates, target - candidates[i], res, comb, i+1);
comb.pop_back();
}
}
void combinationSum2Helper(vector<int>& num, int gap, int begin,
vector<int>& v,vector<vector<int>> &ans) {
if (gap == 0) {
ans.emplace_back(v);
return;
}
for (size_t i = begin; i < num.size() && num[i] <= gap; ++i) {
if ( i == begin || num[i] != num[i - 1]) { // Skip duplicates.
// Each same element could be chosen only once
// with the same previous nums.
v.emplace_back(num[i]);
combinationSum2Helper(num, gap - num[i], i + 1, v, ans);
v.pop_back();
}
}
}
void backtarck(vector<vector<int> >res, vector<bool> flag,vector<int> tmp, vector<int> candidates,int target)
{
if(target == 0)
{
bool found = false;
for(vector<vector<int> >::iterator it = res.begin(); it!= res.end();it++)
{
if(tmp == *it)
{
found = true;
break;
}
}
if(!found)
res.push_back(tmp);
return;
}
else if (target < 0)
{
return;
};
int max = 0;
for (int i = 0; i < tmp.size(); ++i)
{
if(tmp[i] > max)
max = tmp[i]
}
for (int i = 0; i < candidates.size(); ++i)
{
if(!flag[i] && candidates[i] >= max)
{
flag[i] = true;
tmp.push_back(candidates[i]);
combinationSum2Helper(ans, flag, tmp, candidates, target - candidates[i]);
tmp.pop_back();
flag[i] = false;
}
}
}