Combination Sum II

难度：2

还是DFS裸搜，1Y失败了

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> >ans;vector<int>tmp;vector<bool>flag;//是否被使用了void dfs(int left, int cur_index,vector<int> &candidates){if(left == 0){ans.push_back(tmp);return;}for(int i=cur_index;i<candidates.size();i++){if(i-1>=0 && candidates[i] == candidates[i-1] && flag[i-1] == false)continue;if(left-candidates[i] >= 0){tmp.push_back(candidates[i]);flag[i]=true;dfs(left-candidates[i],i+1,candidates);tmp.pop_back();flag[i]=false;}}}    vector<vector<int> > combinationSum2(vector<int> &candidates, int target) {sort(candidates.begin(),candidates.end());ans.clear();tmp.clear();flag.assign(candidates.size(),false);dfs(target,0,candidates);return ans;    }};