problem_12.js

/**
Problem 12
The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...

Let us list the factors of the first seven triangle numbers:

 1: 1
 3: 1,3
 6: 1,2,3,6
10: 1,2,5,10
15: 1,3,5,15
21: 1,3,7,21
28: 1,2,4,7,14,28
We can see that 28 is the first triangle number to have over five divisors.

What is the value of the first triangle number to have over five hundred divisors?
*/
var m = require('./math');

function divisors(x){
    var divs = 0;
    for(var j=1;j<=x;j++){
        if(x%j===0){
            divs++;
        }
    }
    return divs;
}
var d = Date.now();
var n = 1, p=0,x =0, f=0;
while(x<=500){
    p+=n;
    n+=1;
    x = divisors(p);
    if(x > f){
        console.log(p,x,Date.now()-d+'ms');
        f=x;
    }
}
console.log('solution',p,x);