# 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 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]
``````

## Solution

Similar to Combination Sum I, except for line `*` && `**`.

``````public class Solution {
public List<List<Integer>> combinationSum2(int[] num, int target) {
List<List<Integer>> res = new ArrayList<List<Integer>>();
Arrays.sort(num);
ArrayList<Integer> path = new ArrayList<Integer>();
combinationSumRe(num, target, 0, path, res);
return res;
}
void combinationSumRe(int[] candidates, int target, int start, ArrayList<Integer> path, List<List<Integer>> res) {
if (target == 0) {
ArrayList<Integer> p = new ArrayList<Integer>(path);
return;
}
for (int i = start; i < candidates.length && target >= candidates[i]; ++i) {
if (i!=start && candidates[i-1] == candidates[i]) continue; // *
combinationSumRe(candidates,
target-candidates[i], i+1, path, res); // **
path.remove(path.size() - 1);
}
}
}
``````