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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] 

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class Solution {public:    vector<vector<int> > res;    vector<int> path;    vector<int> candidates;    int target;        void solve(int start, int sum){        if(sum > target) return;        if(sum == target){            res.push_back(path);            return;        }        for(int i = start; i < candidates.size(); ++ i){            path.push_back(candidates[i]);            solve(i,sum+candidates[i]);            path.pop_back();        }    }    vector<vector<int> > combinationSum(vector<int> &candidates, int target) {        this->candidates = candidates;        this->target = target;        sort(this->candidates.begin(),this->candidates.end());        solve(0,0);        return res;    }};