2.23力扣-回溯组合总和 III

 216. 组合总和 III - 力扣（LeetCode）

一：Java

(很快写出来)

class Solution {List<Integer> list=new LinkedList<>();List<List<Integer>> ans = new LinkedList<>();int sum=0;public List<List<Integer>> combinationSum3(int k, int n) {df(k, n, 1);return ans;}public void df(int k, int n,int start){if(k==list.size()&&sum==n){ans.add(new LinkedList<>(list));return;}for (int i = start; i <=9; i++) {list.add(i);sum+=i;df(k, n, i+1);sum-=i;list.removeLast();}}
}