题解 | #学英语#

这道题的思路就是三个三个的处理，根据题目要求实现就行了

#include <algorithm>
#include <vector>
#include <map>

using namespace std;

vector<string> v = {
    "and",
    "hundred",
    "thousand",
    "million",
    "billion"
};
map<int,string> mtwenty = {
    {1,"one"},{2,"two"},{3,"three"},{4,"four"},{5,"five"},{6,"six"},{7,"seven"},
    {8,"eight"},{9,"nine"},{10,"ten"},{11,"eleven"},{12,"twelve"},{13,"thirteen"},
    {14,"fourteen"},{15,"fifteen"},{16,"sixteen"},{17,"seventeen"},
    {18,"eighteen"},{19,"nineteen"}
    
};
map<int,string> mhundred = {
    {2,"twenty"},{3,"thirty"},{4,"forty"},{5,"fifty"},{6,"sixty"},
    {7,"seventy"},{8,"eighty"},{9,"ninety"}
};

void mytransform(long long  x,int cnt,string &out){
    string space = " ";
    string temp;
    if(x<20) temp = mtwenty[x];
    else if(x<100){
        int hundred = x/10;
        int r1 = x%10;
        if(r1==0)temp = mhundred[hundred];
        else temp = mhundred[hundred]+' '+mtwenty[r1];
    }
    else if(x<1000){
        int thousand = x/100;
        int r1 = x%100;
        
        int hundred = r1/10;
        int r2 = r1%10;
        if(r1==0) temp = mtwenty[thousand]+space+v[1];
        else if(hundred==0)temp = mtwenty[thousand]+space+v[1]+
            " and "+mtwenty[r2];
        else if(r2==0) {
            if(hundred>1) temp = mtwenty[thousand]+space+v[1]+
                " and "+mhundred[hundred];
            else temp = mtwenty[thousand]+space+v[1]+" and "+mtwenty[r1];
        }
        else {
            if(r1<20)temp = mtwenty[thousand]+space+v[1]+" and "+mtwenty[r1];
            else temp = mtwenty[thousand]+space+v[1]+" and "+
                mhundred[hundred]+' '+mtwenty[r2];
        }
    }
    
    
    if(cnt>1)out = temp+space+v[cnt]+space+out;
    else out = temp+space+out;
    
}

int main() {
    long long n;
    while(cin>>n){
        long long &q = n,r = 0;
        string out;
        int cnt = 1;
        while(q){
            r = q%1000;
            q = q/1000;
            mytransform(r, cnt,out);
            cnt++;
        }
        cout<<out<<endl;
    }
}