|
?
?
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.
- 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] 源码：Java版本
算法分析：时间复杂度O(n!)，空间复杂度O(n)
?
public class Solution {
public List
> combinationSum2(int[] candidates,
int target) {
if (candidates == null) {
return null;
}
Set
> results = new HashSet
>(); Stack
stack = new Stack
(); Arrays.sort(candidates); DFS(candidates,0, target, stack, results); return new ArrayList
>(results); } @SuppressWarnings(unchecked) private void DFS(int[] candidates,int start, int target, Stack
stack, Set
> results) { if (target == 0) { results.add((Stack
) (stack.clone())); } for (int i = start; i < candidates.length; i++) { stack.push(candidates[i]); if (target - candidates[i] >= 0) { DFS(candidates, i+1,target - candidates[i], stack, results); } stack.pop(); } } }
?
|