欧拉工程第17题

题目链接：https://projecteuler.net/problem=17
求1-1000 的英语单词，字母个数之和
下面方法来自网络，注释已经很详细。

package projecteuler11to20;

import java.util.Date;

class level17{
    void solve(){
    String[] nums={"","one","two","three","four","five","six","seven","eight","nine","ten",
            "eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nighteen"};
    String[] tens={"","","twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"};

    int total=0;
    for(int i=1;i<20;i++){// 1-19
        total+=nums[i].length();
    }
    for(int i=20;i<100;i++){//20-99
        int ge=i%10;
        int shi=i/10;
        total+=tens[shi].length()+nums[ge].length();
    }

    total*=10;//1-99 这个会出现10次， X(01) X(99)
    for(int i=1;i<10;i++){
        total+=(nums[i].length()+10)*100;// 就是上面的X的，百位 1xy 2xy 3xy -9xy//10是：hundred and 
        total-=3;//减去3，是在整百位100 200.。。不需要and
    }
    total+=11;//1000
    System.out.println("1-1000英语字母和："+total);
    }
}
public class Problem17 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Date beginTime=new Date();
        new level17().solve();
        Date endTime=new Date();
        long Time=endTime.getTime()-beginTime.getTime();
        System.out.println("Time="+Time/1000+"秒"+Time%1000+"毫秒");
    }
}