用java实现数到3退出（一群小朋友围成一个圈，数到3的朋友自动退出该圈） Count3Quit.java的源代码如下 [code lang="java"] package com.daozhao; public class Count3Quit { public static void main(String[] args){ KidCircle kc=new KidCircle(500); int CountNum=0; Kid k=kc.first; while(kc.count>1){ CountNum++; if (CountNum==3){ CountNum=0; kc.delete(k); } k=k.right; } System.out.println(kc.first.id); } } class Kid{ int id; Kid right; Kid left; } class KidCircle{ int count=0; Kid first; Kid last; KidCircle(int n){ for(int i=0;i<n;i++){ add(); } } void add(){ Kid k=new Kid(); k.id=count; if (count==0){ first=k; last=k; k.left=k; k.right=k; } else{ last.right=k; k.left=last; k.right=first; first.left=k; } count++; } void delete(Kid k){ if(count<=0){ return; } else if(count==1){ first=last=null; } else{ k.left.right=k.right; k.right.left=k.left; if(k==first){ first=k.right; } else if(k==last){ last=k.left; } } count--; } } [/code]