LeetCode 39. Combination Sum

Given a set of candidate numbers (C) (without duplicates) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

The same repeated number may be chosen from C unlimited number of times.

Note:
All numbers (including target) will be positive integers.
The solution set must not contain duplicate combinations.
For example, given candidate set [2, 3, 6, 7] and target 7,
A solution set is:

[
  [7],
  [2, 2, 3]
]

题意：给我们一个数组，我们需要将数组中任意的数字组合（可以重复）相加结果等于给我们的target，我们要将所有可能的组合记录下来。

java代码：

public List> combinationSum(int[] candidates,
            int target) {
        Arrays.sort(candidates);
        List> result = new ArrayList>();
        getResult(result, new ArrayList(), candidates, target, 0);
        return result;
    }
 
    public void getResult(List> result,
            List current, int[] candiates, int target, int start) {
        if (target > 0) {
            for (int i = start; i < candiates.length && target >= candiates[i]; i++) {
                current.add(candiates[i]);
                getResult(result, current, candiates, target - candiates[i], i);
                current.remove(current.size() - 1);
            }
        } else if (target == 0) {
            result.add(new ArrayList(current));
        }
    }