poj2121

字符串处理，还是用string类比较容易，先将字符串用million和thousand切分成三段，然后用同样的方法处理这三段即可。

注意输入数据结尾有多余空行

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
using namespace std;

string name[] =
{ "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety" };
int id[] =
{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 30, 40, 50, 60, 70, 80, 90 };

int getid(string st)
{
    for (int i = 0; i < 27; i++)
        if (st == name[i])
            return id[i];
    return -1;
}

int toint(string st)
{
    if (st == "zero")
        return 0;
    int ret = 0;
    int pos;
    if ((pos = st.find("hundred")) != string::npos)
    {
        ret += getid(st.substr(0, pos - 1)) * 100;
        if (st.length() >= pos + 8)
            st.erase(0, pos + 8);
        else
            st.erase(0, pos + 7);
    }
    if ((pos = st.find(" ")) != string::npos)
    {
        ret += getid(st.substr(0, pos));
        if (st.length() >= pos + 1)
            st.erase(0, pos + 1);
        else
            st.erase(0, pos);
    }
    if (st.length() > 0)
        ret += getid(st);
    return ret;
}

int main()
{
    //freopen("D:\\t.txt", "r", stdin);
    string st;
    while (getline(cin, st) && st != "")
    {
        int ans = 0;
        int pos;
        int ne = 1;
        if (st.substr(0, 8) == "negative")
        {
            ne = -1;
            st.erase(0, 9);
        }
        if ((pos = st.find("million")) != string::npos)
        {
            ans += 1000000 * toint(st.substr(0, pos - 1));
            if (st.length() >= pos + 8)
                st.erase(0, pos + 8);
            else
                st.erase(0, pos + 7);
        }
        if ((pos = st.find("thousand")) != string::npos)
        {
            ans += 1000 * toint(st.substr(0, pos - 1));
            if (st.length() >= pos + 9)
                st.erase(0, pos + 9);
            else
                st.erase(0, pos + 8);
        }
        if (st.length() > 0)
            ans += toint(st);
        ans *= ne;
        printf("%d\n", ans);
    }
    return 0;
}