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40. Combination Sum II (Recursion)

时间:2015-10-05 09:14:32      阅读:219      评论:0      收藏:0      [点我收藏+]

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

Each number in C may only be used once in the combination.

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 10,1,2,7,6,1,5 and target 8
A solution set is: 
[1, 7] 
[1, 2, 5] 
[2, 6] 
[1, 1, 6] 

class Solution {
public:
    vector<vector<int> > combinationSum2(vector<int> &candidates, int target) {
        results.clear();
        vector<int> result;
        sort(candidates.begin(), candidates.end());
        dfs(candidates, result,target, 0);
        return results;  
    }
    
    void dfs(vector<int> &candidates, vector<int> &result, int target, int depth)
    {
        if(candidates[depth] > target || depth == candidates.size()) return;
        result.push_back(candidates[depth]);
        if(candidates[depth] == target)
        {
            results.push_back(result);
            result.pop_back();
            return;
        }
        dfs(candidates,result, target-candidates[depth], depth+1);
        result.pop_back();
        while(++depth<candidates.size()  && candidates[depth] == candidates[depth-1]); //avoid repetition
        dfs(candidates,result, target, depth);
    }
private:
    vector<vector<int> > results;
};

 

40. Combination Sum II (Recursion)

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原文地址:http://www.cnblogs.com/qionglouyuyu/p/4855328.html

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