题解 | #组合#
组合
https://www.nowcoder.com/practice/7cfd3675cc964ae6818a771ac97ece5f
import java.util.*;
public class Solution {
ArrayList<ArrayList<Integer>> res = new ArrayList<>();
ArrayList<Integer> track = new ArrayList<>();
public ArrayList<ArrayList<Integer>> combine (int n, int k) {
backtrack(1,n,k);
return res;
}
private void backtrack(int start,int n,int k){
if(track.size() == k){
res.add(new ArrayList(track));
return;
}
for(int i = start;i<=n;i++){
track.add(i);
backtrack(i+1,n,k);
track.remove(track.size()-1);
}
}
}
