LeetCode刷题【Array】 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.
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]
]

解决方法： 回溯法
public class Solution {
public List<List<Integer>> combinationSum2(int[] candidates, int target) {
List<List<Integer>> result = new ArrayList<>();
Arrays.sort(candidates);
backTrack(candidates,0,target,new ArrayList<>(),result);
return result;
}

private void backTrack(int[] candidates, int start, int target, List<Integer> tempSet, List<List<Integer>> ret){
if(target==0) ret.add(new ArrayList<>(tempSet));
else if(target<0||start>=candidates.length) return;
else{
for(int i=start;i<candidates.length;i++){
if(i>=start+1&&candidates[i]==candidates[i-1]) continue;
tempSet.add(candidates[i]);
backTrack(candidates, i+1,target-candidates[i],tempSet,ret);
tempSet.remove(tempSet.size()-1);
}
}
}
}参考：

【1】https://leetcode.com/