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CombinationSumII.java
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CombinationSumII.java
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/**
* 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]
*/
import java.util.ArrayList;
import java.util.Arrays;
public class CombinationSumII {
public ArrayList<ArrayList<Integer>> combinationSum2(int[] candidates,
int target) {
ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
ArrayList<Integer> list = new ArrayList<Integer>();
Arrays.sort(candidates);
dfs(res, 0, candidates, list, target);
return res;
}
private void dfs(ArrayList<ArrayList<Integer>> res, int start,
int[] candidates, ArrayList<Integer> list, int target) {
if (target == 0) {
res.add(new ArrayList<Integer>(list));
return;
}
int pre = -1;
for (int i = start; i < candidates.length; i++) {
if (pre == candidates[i])
continue;
if (candidates[i] > target)
return;
pre = candidates[i];
list.add(candidates[i]);
dfs(res, i + 1, candidates, list, target - candidates[i]);
list.remove(list.size() - 1);
}
}
}