Combination Sum II | Java最短代码实现

原题链接： 40. Combination Sum II 基础博文： Combination Sum

【思路】

和 Combination Sum 十分类似，都是用回溯算法。只不过candidates中含有重复元素，要求不能有重复组合：

    public List<List<Integer>> combinationSum2(int[] candidates, int target) {
        ArrayList<List<Integer>> result = new ArrayList<List<Integer>>();
        ArrayList<Integer> temp = new ArrayList<Integer>();
        Arrays.sort(candidates);
        findCandidates(candidates, target, 0, result, temp);
        return result;
    }
    public void findCandidates(int[] candidates, int target, int curIndex, List<List<Integer>> result, List<Integer> temp) {
        if (0 == target) {
            result.add(new ArrayList<Integer>(temp));
        }
        for (int i = curIndex; i < candidates.length && candidates[i] <= target; i++) {
            if (i > curIndex && candidates[i] == candidates[i - 1]) continue; //去重
            temp.add(candidates[i]);
            findCandidates(candidates, target - candidates[i], i + 1, result, temp);
            temp.remove(temp.size() - 1);
        }
    }

172 / 172  test cases passed. Runtime: 4 ms  Your runtime beats 93.46% of javasubmissions.

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