约瑟夫环-递归

package JianZhioffer;

import java.util.ArrayList;
import java.util.List;

public class test62 {
    public static void main(String[] args) {
        int n=5;
        int m=2;
        System.out.println(lastRemaining(n, m));    
    }
  //最后一个元素时候删除得是第0个，假设n-1元素删除第x个，那么n元素删除(m+x)%n
    public static int lastRemaining(int n, int m) {
        return f(n, m);
    }

    public static int f(int n, int m) {
        if (n == 1) {
            return 0;
        }
        int x = f(n - 1, m);
        return (m + x) % n;
    }
    //超时
    public static int lastRemaining1(int n, int m) {
        if(n==1){
            return 0;
        }
        if(m==1){
            return n-1;
        }
        ListNode list=new ListNode(0);
        ListNode x=list;
        for(int i=1;i<n;i++){
            list.next=new ListNode(i);
            list=list.next;
        }
        list.next=x;
        ListNode list1=x;
        
        while(list1.next!=list1){
            int l=1;
            int k=1;
            ListNode list2=list1;
            while(k<m-1){
                list2=list2.next;
                k++;
            }
            ListNode list4=list2.next.next;
            
           
            // ListNode list2=list1.next;
            list2.next=list4;
            list1=list4;
            // list4.next=list1;
        }
        return list1.val;
    }
}