LeetCode Combination Sum II

题目：

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> &num, int target) {sort(num.begin(), num.end());res.clear();dfs(0, num.size(), num, target);return res;}private://表示第i个数字要还是不要int a[1000];vector<vector<int> > res;void dfs(int dep, int maxDep, vector<int> &num, int target) {if (target < 0)return;if (target == 0) {vector<int> ans;for (int i = 0; i < dep; i++) {if (a[i])ans.push_back(num[i]);}res.push_back(ans);return;}if (dep == maxDep)return;for (int i = 0; i <= min(target / num[dep], 1); i++) {a[dep] = i;if (i == 1 && dep != 0 && num[dep] == num[dep - 1] && a[dep - 1] == 0)continue;dfs(dep + 1, maxDep, num, target - num[dep] * i);}}};