HDU 2024

#include<iostream>#include<cctype>#include<string>using namespace std;int main(){    int n, length;    string line;    char t;    bool con, res;    while(cin >> n)    {        getline(cin, line);        while(n--)        {            getline(cin, line);            length = line.size();            res = con = true;            if(!(isalpha(line[0])))                if(line[0] != '_')                    con = res = false;            for(int i = 1; i < length && con; i++)                if(!(isalnum(line[i])))                    if(!(isdigit(line[i])))                        if(line[i] != '_')                            con = res = false;            if(res)                cout << "yes" << endl;            else                cout << "no" << endl;        }    }    return 0;}