Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.
Each number in candidates 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.
Example 1:
Input: candidates =[10,1,2,7,6,1,5], target =8, A solution set is: [ [1, 7], [1, 2, 5], [2, 6], [1, 1, 6] ]
Example 2:
Input: candidates = [2,5,2,1,2], target = 5, A solution set is: [ [1,2,2], [5] ]
注意需要排序
1 class Solution { 2 private List<List<Integer>> res = new ArrayList<>(); 3 public List<List<Integer>> combinationSum2(int[] candidates, int target) { 4 List<Integer> temp = new ArrayList<Integer>(); 5 Arrays.sort(candidates); 6 help(temp,candidates,0,0,target); 7 return res; 8 } 9 private void help(List<Integer> temp,int[] nums,int index,int cursum,int target){ 10 if(cursum>target) 11 return; 12 else if(cursum==target) 13 res.add(new ArrayList<Integer>(temp)); 14 else{ 15 for(int i = index;i<nums.length;i++){ 16 if(i > index && nums[i] == nums[i-1]) continue; // skip duplicates 17 temp.add(nums[i]); 18 help(temp,nums,i+1,cursum+nums[i],target); 19 temp.remove(temp.size()-1); 20 } 21 } 22 } 23 }
1 class Solution: 2 def __init__(self): 3 self.res = [] 4 def combinationSum2(self, candidates, target): 5 """ 6 :type candidates: List[int] 7 :type target: int 8 :rtype: List[List[int]] 9 """ 10 def help(x,temp,index,cursum,t): 11 temp = temp[:] 12 if cursum>t: 13 return 14 if(cursum==t): 15 self.res.append(temp) 16 for i in range(index,len(x)): 17 if(i > index and x[i]==x[i-1]): 18 continue 19 temp.append(x[i]) 20 help(x,temp,i+1,cursum +x[i],t) 21 temp.pop(-1) 22 23 24 x = sorted(candidates) 25 help(x,[],0,0,target) 26 return self.res 27 28
与上一个题目不同，这个题要求每个数字只能用一次，
所以需要从i+1开始搜索（代码18行）
candidates 中可能会有重复的元素
[10,1,2,7,6,1,5]
8
如果没有19行，结果为
Your answer
[[1,1,6],[1,2,5],[1,7],[1,2,5],[1,7],[2,6]]
Expected answer
[[1,2,5],[1,7],[1,1,6],[2,6]]
因为 1,1,2,5,6,7,10
第一个1会生成结果125,17
第二个1也会生成125,17
2019.3.12
1 class Solution { 2 public: 3 vector<vector<int>> finalres ; 4 vector<vector<int>> combinationSum2(vector<int>& candidates, int target) { 5 if(candidates.size()==0) return finalres; 6 sort(candidates.begin(),candidates.end()); 7 vector<int> curres; 8 help(0,curres,candidates,0,target); 9 return finalres; 10 11 } 12 void help(int cursum,vector<int>& curres,vector<int>& candidates,int index,int target){ 13 if(cursum==target) 14 finalres.push_back(curres); 15 if(cursum>target) 16 return; 17 for(int i = index;i<candidates.size();i++){ 18 if(i >index && candidates[i]==candidates[i-1]) continue; 19 curres.push_back(candidates[i]); 20 help(cursum,curres,candidates,i+1,target-candidates[i]); 21 curres.pop_back(); 22 23 } 24 } 25 };