标签：div else pre ++ numbers style question move i+1
Given two integers n and k, return all possible combinations of k numbers out of 1 ... n.
For example,
If n = 4 and k = 2, a solution is:
[ [2,4], [3,4], [2,3], [1,2], [1,3], [1,4], ]
本题也是采用回溯法，做法与之前的比较类似，代码如下：
1 public class Solution { 2 public List<List<Integer>> combine(int n, int k) { 3 List<List<Integer>> res= new ArrayList<>(); 4 backtracking(res,new ArrayList<Integer>(),n,k,1); 5 return res; 6 } 7 public void backtracking(List<List<Integer>> res,List<Integer> list,int n,int k,int cur){ 8 if(k==0) res.add(new ArrayList<Integer>(list)); 9 else if(k<0) return; 10 else if(k>0){ 11 for(int i=cur;i<=n;i++){ 12 list.add(i); 13 backtracking(res,list,n,k-1,i+1); 14 list.remove(list.size()-1); 15 } 16 } 17 } 18 }
标签：div else pre ++ numbers style question move i+1
原文地址：http://www.cnblogs.com/codeskiller/p/6390414.html
