60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/* 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.
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* The first ten terms would be:
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*
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* 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...
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*
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* Let us list the factors of the first seven triangle numbers:
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*
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* 1: 1
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* 3: 1,3
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* 6: 1,2,3,6
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* 10: 1,2,5,10
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* 15: 1,3,5,15
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* 21: 1,3,7,21
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* 28: 1,2,4,7,14,28
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*
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* We can see that 28 is the first triangle number to have over five divisors.
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*
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* What is the value of the first triangle number to have over five hundred divisors?*/
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#define _POSIX_C_SOURCE 199309L
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#include <stdio.h>
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#include <stdlib.h>
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#include <time.h>
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#include "projecteuler.h"
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int main(int argc, char **argv)
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{
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int i = 0, finished = 0, count, triang = 0;
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double elapsed;
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struct timespec start, end;
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clock_gettime(CLOCK_MONOTONIC, &start);
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/* Generate all triangle numbers until the first one with more than 500 divisors is found.*/
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while(!finished)
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{
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i++;
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triang += i;
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/* Use the function implemented in projecteuler.c to count divisors of a number.*/
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count = count_divisors(triang);
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if(count > 500)
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{
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finished = 1;
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}
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}
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clock_gettime(CLOCK_MONOTONIC, &end);
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elapsed = (end.tv_sec - start.tv_sec) + (double)(end.tv_nsec - start.tv_nsec) / 1000000000;
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printf("Project Euler, Problem 12\n");
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printf("Answer: %d\n", triang);
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printf("Elapsed time: %.9lf seconds\n", elapsed);
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return 0;
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}
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