Problem 42 Coded triangle numbers（ifstream +getline）

Coded triangle numbers

Problem 42

The nth term of the sequence of triangle numbers is given by, tn = ½n(n+1); so the first ten triangle numbers are:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
By converting each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 = t10. If the
word value is a triangle number then we shall call the word a triangle word.

Using words.txt (right click and 'Save Link/Target As...'), a 16K text
file containing nearly two-thousand common English words, how many are triangle words?

Answer: 162 Completed on Sun, 30 Oct 2016, 07:00

题解：ifstream +getline ...



代码：

#include <iostream>
#include <string>
#include <fstream>
#include <cmath>

using namespace std;

int wordScore(string a)
{
int score = 0;

for(int i=0;i<a.length();i++)
{
if(a[i]>=65&&a[i]<=90)
score +=( a[i]-'A'+1 );
}
return score;
}

bool isTriangular(int a)
{
double m = (sqrt(8*(double)a+1) - 1) / 2;
if(floor(m)==m) return true;
return false;
}

int main()
{
int ans = 0;
string word;
ifstream fin("words.txt");
if (fin.is_open())
{
while (getline(fin,word,','))
{
if(isTriangular( wordScore(word) ) )
{
ans++;
}
}
fin.close();
}
cout << ans << endl;
return 0;
}