[Leetcode]Combination Sum

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in
C where the candidate numbers sums to T.

The same repeated number may be chosen from C unlimited number of times.

Note:

All numbers (including target) will be positive integers.
Elements in a combination (a1, a2, … ,
ak) must be in non-descending order. (ie, a1 ≤
a2 ≤ … ≤ ak).
The solution set must not contain duplicate combinations.

For example, given candidate set

2,3,6,7

and target

7

,

A solution set is:

[7]

[2, 2, 3]

class Solution {
public:
/*dfs
*/
void dfs(vector<vector<int>>&result,vector<int>&path,int start,vector<int>&vec,int n){
if(n==0){//one solution
result.push_back(path);
return;
}
for(int i = start;i < vec.size();i++){
if(vec[i] > n)continue;
path.push_back(vec[i]);
dfs(result,path,i,vec,n-vec[i]);
path.pop_back();
}
}
vector<vector<int>> combinationSum(vector<int>& candidates, int target) {
vector<vector<int>>result;
vector<int>path;
sort(candidates.begin(),candidates.end());
dfs(result,path,0,candidates,target);
return result;
}
};