题解 | #学英语#

#include <iostream>
#include <vector>

using namespace std;

/* 获取对应数字的 英文 */
string get_value(int data)
{
    string value;
    
    switch(data)
    {
        case 1: value = "one"; break;
        case 2: value = "two"; break;
        case 3: value = "three"; break;
        case 4: value = "four"; break;
        case 5: value = "five"; break;
        case 6: value = "six"; break;
        case 7: value = "seven"; break;
        case 8: value = "eight"; break;
        case 9: value = "nine"; break;
        case 10: value = "ten"; break;
        case 11: value = "eleven"; break;
        case 12: value = "twelve"; break;
        case 13: value = "thirteen"; break;
        case 14: value = "fourteen"; break;
        case 15: value = "fifteen"; break;
        case 16: value = "sixteen"; break;
        case 17: value = "seventeen"; break;
        case 18: value = "eighteen"; break;
        case 19: value = "nineteen"; break;
        case 20: value = "twenty"; break;
        case 30: value = "thirty"; break;
        case 40: value = "forty"; break;
        case 50: value = "fifty"; break;
        case 60: value = "sixty"; break;
        case 70: value = "seventy"; break;
        case 80: value = "eighty"; break;
        case 90: value = "ninety"; break;
        default: value = "";break;
    }
    
    return value;
}

/* 对应单位的 英文 */
string get_unit_value(int data)
{
    string value;
    
    switch(data % 3)
    {
        case 0: value = "hundred"; break;
        case 1: value = "thousand"; break;
        case 2: value = "million"; break;
        case 3: value = "billion"; break;
        default: value = "";break;
    }
    
    return value;
}

int main()
{
    long num;
    vector<string> en_num;
    int index = 0;
    while(cin >> num)
    {
        while(num)
        {
            int mod = num % 1000;
            
            /* 获取个位英文 */
            en_num.push_back(get_value(mod % 10));
            if(mod >= 10)
            {
                int tmp;
                if(mod % 100 < 20) /* 10-20 之间英文 */
                {
                    tmp = mod % 100;
                    en_num.pop_back();    /* 注意10-20 时，需将前面已存 个位删除 */
                    en_num.push_back(get_value(tmp));
                }
                else            /* 10和 20 - 99以上 英文 */
                {
                    tmp = mod / 10 * 10 % 100;        
                    en_num.push_back(get_value(tmp));
                }
                
                if(mod >= 100)    /* 百位英文 */
                {
                    if(tmp || mod % 10) /* 百位后面位数不为 0 需添加 and */
                    {
                        en_num.push_back("and");
                    }
                    
                    en_num.push_back(get_unit_value(0));
                    en_num.push_back(get_value(mod / 100));
                }
                
            }
            
            num /= 1000;
            if(num)
            {
                ++index;                
                en_num.push_back(get_unit_value(index));
            }
        }
        
        for(auto s = en_num.rbegin(); s != en_num.rend(); s++)
        {
            if(*s != "")        //可能存在 空字符，不应输出 
            {
                cout << *s << " ";
            }
            
        }
        cout << endl;
        
    }
    return 0;
}