47 lines
1.2 KiB
C
47 lines
1.2 KiB
C
/* The sum of the squares of the first ten natural numbers is,
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*
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* 1^2 + 2^2 + ... + 10^2 = 385
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*
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* The square of the sum of the first ten natural numbers is,
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*
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* (1 + 2 + ... + 10)^2 = 55^2 = 3025
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*
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* Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 − 385 = 2640.
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*
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* Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.*/
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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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int main(int argc, char **argv)
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{
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int i, sum_squares = 0, square_sum = 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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/* Straightforward brute-force approach.*/
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for(i = 1; i <= 100; i++)
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{
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sum_squares += i*i;
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square_sum += i;
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}
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square_sum *= square_sum;
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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 6\n");
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printf("Answer: %d\n", square_sum-sum_squares);
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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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