/* The series, 1^1 + 2^2 + 3^3 + ... + 10^10 = 10405071317.
 *
 * Find the last ten digits of the series, 1^1 + 2^2 + 3^3 + ... + 1000^1000.*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <gmp.h>

#define _POSIX_C_SOURCE 199309L

int main(int argc, char **argv)
{
    int i;
    double elapsed;
    struct timespec start, end;
    mpz_t power, sum;
    char *res;

    clock_gettime(CLOCK_MONOTONIC, &start);

    mpz_init_set_ui(sum, 0);
    mpz_init(power);

    /* Simply calculate the sum of the powers using the GMP Library.*/
    for(i = 1; i <= 1000; i++)
    {
        mpz_ui_pow_ui(power, i, i);
        mpz_add(sum, sum, power);
    }

    res = mpz_get_str(NULL, 10, sum);

    mpz_clears(power, sum, NULL);

    clock_gettime(CLOCK_MONOTONIC, &end);

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

    printf("Project Euler, Problem 48\n");
    printf("Answer: %s\n", res+strlen(res)-10);

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

    return 0;
}