【leetcodeブラシノート】Combination Sum II

Given a collection of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums toT.
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]  
 
Combination Sumとの違いは上の赤い行で、再帰時の起点をiからi+1に変更すれば、以下のコードでハイライトされている部分を参照してください.
コードは次のとおりです.

 1 public class Solution {

 2     private void combiDfs(int[] candidates,int target,List<List<Integer>> answer,List<Integer> numbers,int start){

 3         if(target == 0){

 4             answer.add(new ArrayList<Integer>(numbers));

 5             return;

 6         }

 7         

 8         int prev = -1;

 9         

10         for(int i = start;i < candidates.length;i++){

11             if(candidates[i] > target)

12                 break;

13             if(prev != -1 && prev == candidates[i])

14                 continue;

15             

16             numbers.add(candidates[i]);

17             combiDfs(candidates, target-candidates[i], answer, numbers,i+1); 18             numbers.remove(numbers.size()-1);

19             

20             prev = candidates[i];

21         }

22     }

23     public List<List<Integer>> combinationSum2(int[] candidates, int target) {

24         List<List<Integer>> answer = new ArrayList<List<Integer>>();

25         List<Integer> numbers = new ArrayList<Integer>();

26         Arrays.sort(candidates);

27         combiDfs(candidates, target, answer, numbers,0);

28         

29         return answer;

30         

31     }

32 }