LeetCode OJ:Combination Sum

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 (a1a2, … , 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] 

算法思想:暴搜

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



LeetCode OJ:Combination Sum

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