第05章 数组 12 练习 10

鱼欲遇雨：每日都学习一点，持之以恒，天道酬勤！不能用电脑时，提前补上！（2012.8.23）

注：23号回学校，提前补这一天！

小练习：

500个人，一个人开始数，1,2,3,1,2,3.。。是3的人退出，一直循环都最后一个人，这个人是第几个人？（面向对象的解法）（完整代码）

//Count3Quit2.java

public class Count3Quit2 {
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 left;
Kid right;
}

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;
last = k;
}
count++;
}

void delete(Kid k) {
if(count == 0) {
return;
}else if(count == 1) {
first = last = null;
}else {
k.right.left = k.left;
k.left.right = k.right;

if(k == first) {
first = k.right;
}else if(k == last) {
last = k.left;
}
}
count--;
}
}