常规写法实现手拉手遇三退一的游戏，可以和面向对象思想进行比较着看

public class Count3Quit {
public static void main(String[] args) {
int[] a = new int[500];            // 500人的环
for(int i=0; i<a.length; i++) {
a[i] = 1;
}

int leftCount = 500;
int countNum = 0;
int index = 0;

while(leftCount != 1) {
if(a[index] == 1) {
countNum ++;
if(countNum == 3) {
countNum = 0;
a[index] = 0;
leftCount --;
}
}

index ++;
if(index == a.length) {
index = 0;
}
}

for(int i=0; i<a.length; i++) {
if(a[i] == 1) {
System.out.println(i);
}
}
}
}