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] ]
題解如下：
class Solution {
public List<List<Integer>> combinationSum2(int[] candidates, int target) {
List<List<Integer>> res = new ArrayList<>();
List<Integer> tmp = new ArrayList<>();
Arrays.sort(candidates);
backtrack(res,tmp,candidates,target,0);
return res;
}
public void backtrack(List<List<Integer>> res,List<Integer> tmp,
int[] candidates,int target,int idx) {
if(target == 0) {
res.add(new ArrayList(tmp));
return;
}
for(int i = idx;i < candidates.length;i++) {
if(i > idx && candidates[i] == candidates[i- 1])
continue;
if(target >= candidates[i]) {
target -= candidates[i];
tmp.add(candidates[i]);
backtrack(res,tmp,candidates,target,i+1);
tmp.remove(tmp.size()-1);
target += candidates[i];
}
}
}
}