[LeetCode]Combination Sum

class Solution {
//DFS
//sort candidates first and then DFS
public:
vector<vector<int> > combinationSum(vector<int> &candidates, int target) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
sort(candidates.begin(), candidates.end());
vector<vector<int>> ans;
vector<int> path;
combinationSum_aux(0, 0, target, path, ans, candidates);
return ans;
}

void combinationSum_aux( int index, int sumNow, int target, vector<int> path, vector<vector<int>>& ans, vector<int>& candidates )
{
//throw std::exception("The method or operation is not implemented.");
if(sumNow == target)
{
ans.push_back(path);
return;
}
if(index >= candidates.size())
return;
int num = (target-sumNow)/candidates[index];
int cur = 0;
for (int i = 0; i <= num; ++i)
{
combinationSum_aux(index+1, sumNow+cur, target, path, ans, candidates);
path.push_back(candidates[index]);
cur += candidates[index];
}

}

};

class Solution {
public:
void combinationSumUtil(vector<int>& candidates, int target, int curIdx, vector<int> curPath, vector<vector<int> >& allPath)
{
if(target == 0)
{
allPath.push_back(curPath);
return ;
}
if(curIdx >= candidates.size()) return;

if(curIdx >= 1 && candidates[curIdx] == candidates[curIdx-1]) combinationSumUtil(candidates, target, curIdx+1, curPath, allPath);
else
{
int curSum = 0;
do
{
if(target >= curSum) combinationSumUtil(candidates, target-curSum, curIdx+1, curPath, allPath);
curPath.push_back(candidates[curIdx]);
curSum += candidates[curIdx];
}
while(target >= curSum);

}
}
vector<vector<int> > combinationSum(vector<int> &candidates, int target) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
sort(candidates.begin(), candidates.end());
vector<int> curPath;
vector<vector<int> > allPath;
combinationSumUtil(candidates, target, 0, curPath, allPath);
return allPath;
}
};