題目

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]

方法

和上一題思路一樣，只是條件不同了。

    private void getCom(int[] candidates, int target, int start, List subList, List> list) {
        for (int i = start; i < candidates.length; i++) {
        	if (i == start || candidates[i] != candidates[i - 1]) {
                List newList = new ArrayList(subList);            
                if (target - candidates[i] == 0) {
                    newList.add(candidates[i]);
                    list.add(newList);
                } else if (target - candidates[i] > 0) {
                    newList.add(candidates[i]);
                    getCom(candidates, target - candidates[i], i + 1, newList, list);
                } else {
                    break;
                }
        	}
        }
    }
    public List> combinationSum2(int[] num, int target) {
        Arrays.sort(num);
        List> list = new ArrayList>();
        List subList = new ArrayList();
        getCom(num, target, 0, subList, list);
        return list;
    }