042.cpp

#include <iostream>
#include <fstream>
using namespace std;

int char_idx(char c)
{
        return c-'A'+1;
}

bool is_triangle_no(unsigned x)
{
        //solve x=n*(n+1)/2 by iteration
        float n=0;
        float n1=0;
        do {
                n=n1;
                n1 = x/(n+1)+n/2;
        } while (n!=n1);

        if (x == (unsigned)n*(n+1)/2)return 1;
        else return 0;
}

int main()
{
        ifstream fin;
        fin.open("042.txt");


        unsigned count=0;
        char c;
        unsigned word_value=0;
        while (!fin.eof()) {
                fin >> c;

                //ignore character "
                if (c=='"')continue;
                //check & restart word value if encounter ,
                else if (c==',') {
                        if(is_triangle_no(word_value))
                                count++;
                        
                        word_value=0;
                        continue;
                } else
                        word_value+=char_idx(c);
        }
        fin.close();
        
        cout << count << endl;
        return 0;
}