/* 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?*/

#define _POSIX_C_SOURCE 199309L

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "projecteuler.h"

int main(int argc, char **argv)
{
    int i = 0, finished = 0, count, triang = 0;
    double elapsed;
    struct timespec start, end;

    clock_gettime(CLOCK_MONOTONIC, &start);

    /* Generate all triangle numbers until the first one with more than 500 divisors is found.*/
    while(!finished)
    {
        i++;
        triang += i;
        /* Use the function implemented in projecteuler.c to count divisors of a number.*/
        count = count_divisors(triang);

        if(count > 500)
        {
            finished = 1;
        }
    }

    clock_gettime(CLOCK_MONOTONIC, &end);

    elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;

    printf("Project Euler, Problem 12\n");
    printf("Answer: %d\n", triang);

    printf("Elapsed time: %.9lf seconds\n", elapsed);

    return 0;
}