leetcode 273. Integer to English Words 阿拉伯数字转换为英文表示

太过爱你忘了你带给我的痛 2022-06-08 13:25 148阅读 0赞

Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 - 1.

For example,  
123 -> “One Hundred Twenty Three”  
12345 -> “Twelve Thousand Three Hundred Forty Five”  
1234567 -> “One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven”

这道题不难，就是需要细心+耐心。

代码如下：

/*
     * 这个题不难
     * 就是要细心，注意各种情况的格式的控制输出
     * 这里使用的是String，其实使用StringBuilder可能更快
     * */
    class Solution 
    {
        public String numberToWords(int num) 
        {
            if(num<0)
                return "";
            if(num==0)
                return "Zero";
    
            String[] units = {
       ""," Thousand"," Million"," Billion"};
            String res="";
            int i=0;
            while(num>0)
            {
                int one=num%1000;
                if(one>0)
                    res = getWords(one) + units[i] + (res.length()==0? "": " "+res);
                i++;
                num=num/1000;
            }
            return res;
        }
    
        private String getWords(int num) 
        {
            String res = "";  
            String[] ten = {
       "Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine"};  
            String[] hundred = {
       "Ten", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};  
            String[] twenty = {
       "Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};  
    
            if(num/100>0)
            {
                res = res + ten[num/100]+ " Hundred";
                num=num%100;
            }
    
            if(num>=10 && num<20)
            {
                if(res.length()==0)
                    res=res+twenty[num%10];
                else 
                    res=res+" "+twenty[num%10];
                return res;
            }else if(num>=20)
            {
                int tmp=num/10;
                if(res.length()==0)
                    res=res+hundred[tmp-1];
                else 
                    res=res+" "+hundred[tmp-1];
                 num=num%10;
            }
    
            if(num>0)
            {       
                if(res.length()==0)
                    res=res+ten[num];
                else 
                    res=res+" "+ten[num];
            }
            return res;
        }
    }

下面是C++的做法，是一个很烦的做法，代码如下：

#include <iostream>
    #include <vector>
    #include <map>
    #include <set>
    #include <queue>
    #include <stack>
    #include <string>
    #include <algorithm>
    
    using namespace std;
    
    class Solution
    {
    public:
        static string numberToWords(int n) 
        {
            if (n == 0) 
                return "Zero";
            else 
                return int_string(n).substr(1);
        }
        static const char * const below_20[];
        static const char * const below_100[];
        static string int_string(int n)
        {
            if (n >= 1000000000)   
                return int_string(n / 1000000000) + " Billion" + int_string(n - 1000000000 * (n / 1000000000));
            else if (n >= 1000000) 
                return int_string(n / 1000000) + " Million" + int_string(n - 1000000 * (n / 1000000));
            else if (n >= 1000)    
                return int_string(n / 1000) + " Thousand" + int_string(n - 1000 * (n / 1000));
            else if (n >= 100)     
                return int_string(n / 100) + " Hundred" + int_string(n - 100 * (n / 100));
            else if (n >= 20)      
                return string(" ") + below_100[n / 10 - 2] + int_string(n - 10 * (n / 10));
            else if (n >= 1)       
                return string(" ") + below_20[n - 1];
            else return "";
        }
    };
    
    const char * const Solution::below_20[] = { "One", "Two", "Three", "Four","Five","Six","Seven","Eight","Nine","Ten", "Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen" };
    const char * const Solution::below_100[] = { "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety" };