leetcode--Combination Sum II

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations inC 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, … ,a_k) must be in non-descending order. (ie, a₁ ≤a₂ ≤ … ≤ a_k).
• 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]

[java] view plain copy

1. public class Solution {  
2.     public List<List<Integer>> combinationSum2(int[] candidates, int target) {  
3.         List<List<Integer>> res = new ArrayList<List<Integer>>();  
4.         Arrays.sort(candidates);          
5.         Stack<Integer> stack = new Stack<Integer>();          
6.         dfs(res, stack, target, 0, candidates,0);  
7.         return res;  
8.     }  
9.       
10.     void dfs(List<List<Integer>> res,Stack<Integer> stack,int target,int cur,int[] arr,int sum){        
11.         if(sum==target){              
12.             ArrayList<Integer> data = new ArrayList<Integer>(stack);  
13.             res.add(data);  
14.             return;  
15.         }else if(sum>target) return;  
16.         else{  
17.             int pre = -1;  
18.             for(int i=cur;i<arr.length;i++){  
19.                 if(pre!=arr[i]){//去重  
20.                     stack.add(arr[i]);  
21.                     sum += arr[i];  
22.                     dfs(res, stack, target, i+1, arr,sum);  
23.                     sum -= arr[i];  
24.                     stack.pop();  
25.                     pre = arr[i];  
26.                 }  
27.             }  
28.         }  
29.     }  
30. } 

原文链接http://blog.csdn.net/crazy__chen/article/details/45725657