109 lines
2.3 KiB
C
109 lines
2.3 KiB
C
/* Consider all integer combinations of ab for 2 ≤ a ≤ 5 and 2 ≤ b ≤ 5:
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*
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* 2^2=4, 2^3=8, 2^4=16, 2^5=32
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* 3^2=9, 3^3=27, 3^4=81, 3^5=243
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* 4^2=16, 4^3=64, 4^4=256, 4^5=1024
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* 5^2=25, 5^3=125, 5^4=625, 5^5=3125
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*
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* If they are then placed in numerical order, with any repeats removed, we get the following sequence of 15 distinct terms:
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*
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* 4, 8, 9, 16, 25, 27, 32, 64, 81, 125, 243, 256, 625, 1024, 3125
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*
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* How many distinct terms are in the sequence generated by ab for 2 ≤ a ≤ 100 and 2 ≤ b ≤ 100?*/
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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 <gmp.h>
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#include "projecteuler.h"
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int compare(void *a, void *b);
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int main(int argc, char **argv)
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{
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mpz_t a;
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mpz_t **powers;
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int i, j, count;
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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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if((powers = (mpz_t **)malloc(9801*sizeof(mpz_t *))) == NULL)
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{
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fprintf(stderr, "Error while allocating memory\n");
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return 1;
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}
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for(i = 0; i < 9801; i++)
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{
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if((powers[i] = (mpz_t *)malloc(sizeof(mpz_t))) == NULL)
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{
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fprintf(stderr, "Error while allocating memory\n");
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return 1;
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}
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}
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mpz_init(a);
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for(i = 0; i < 9801; i++)
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{
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mpz_init(*powers[i]);
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}
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/* Using the GMP Library to calculate all the powers.*/
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for(i = 2; i <= 100; i++)
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{
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mpz_set_ui(a, i);
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for(j = 2; j <= 100; j++)
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{
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mpz_pow_ui(*powers[(i-2)*99+j-2], a, j);
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}
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}
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mpz_clear(a);
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/* Sort the values and count the different values.*/
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quick_sort((void **)powers, 0, 9800, compare);
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count = 1;
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for(i = 1; i < 9801; i++)
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{
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if(mpz_cmp(*powers[i], *powers[i-1]))
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{
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count++;
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}
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}
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for(i = 0; i < 9801; i++)
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{
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mpz_clear(*powers[i]);
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free(powers[i]);
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}
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free(powers);
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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 29\n");
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printf("Answer: %d\n", count);
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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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int compare(void *a, void *b)
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{
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mpz_t *n1, *n2;
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n1 = (mpz_t *)a;
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n2 = (mpz_t *)b;
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return mpz_cmp(*n1, *n2);
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}
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