package com.heima.test;
import java.math.BigInteger;
public class Test6 {
/**
* @param args
* 需求:求出1000的阶乘所有零和尾部零的个数,不用递归做
*/
public static void main(String[] args) {
/*int result = 1;
for(int i = 1; i <= 1000; i++) {
result = result * i;
}
System.out.println(result); //因为1000的阶乘远远超出了int的取值范围
*/
//demo1();
demo2();
}
public static void demo2() { //获取1000的阶乘尾部有多少个零
BigInteger bi1 = new BigInteger("1");
for(int i = 1; i <= 1000; i++) {
BigInteger bi2 = new BigInteger(i+"");
bi1 = bi1.multiply(bi2); //将bi1与bi2相乘的结果赋值给bi1
}
String str = bi1.toString(); //获取字符串表现形式
StringBuilder sb = new StringBuilder(str);
str = sb.reverse().toString(); //链式编程
int count = 0; //定义计数器
for(int i = 0; i < str.length(); i++) {
if('0' != str.charAt(i)) {
break;
}else {
count++;
}
}
System.out.println(count);
}
public static void demo1() { //求1000的阶乘中所有的零
BigInteger bi1 = new BigInteger("1");
for(int i = 1; i <= 1000; i++) {
BigInteger bi2 = new BigInteger(i+"");
bi1 = bi1.multiply(bi2); //将bi1与bi2相乘的结果赋值给bi1
}
String str = bi1.toString(); //获取字符串表现形式
int count = 0;
for(int i = 0; i < str.length(); i++) {
if('0' == str.charAt(i)) { //如果字符串中出现了0字符
count++; //计数器加1
}
}
System.out.println(count);
}
}
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