62 lines
1.4 KiB
C
62 lines
1.4 KiB
C
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#include <stdio.h>
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#include <math.h>
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int is_prime(int);
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int populate_array(int * array, size_t size) {
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int index = 0;
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for (int i = 1; i < size; i++) {
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if ( is_prime(i) ) {
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array[index++] = i;
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}
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}
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return index;
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}
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int is_present(int * array, size_t size, int number);
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void parr(int * array, size_t size, size_t numbers) {
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for (int i = 1; i < numbers; i++)
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printf("%d IS PRESENT: %d\n",i, is_present(array, size, i));
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}
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int is_prime(int number) {
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for (int i = 2; i <= number/2; i++) {
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if ( number % i == 0 ) {
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return 0;
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}
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}
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return 1;
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}
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int _is_present(int * array, int number, int low, int high) {
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int middle = ((high + low) / 2.0);
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//printf("L: %d H: %d M: %d N: %d\n", low, high, middle, number);
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if ( number > array[middle] ) {
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return _is_present(array, number, middle, high);
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} else if ( number < array[middle] ) {
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return _is_present(array, number, low, middle);
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} else if ( number == array[middle] ) {
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return 1;
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} else {
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return 0;
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}
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}
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int is_present(int * array, size_t size, int number) {
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if ( is_prime(number) ) {
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return _is_present(array, number, 0, size);
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} else {
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return 0;
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}
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}
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int main(void) {
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int primes[100];
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int real_primes = populate_array(primes, 100);
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//parr(primes, real_primes, 100);
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printf("%d\n", is_present(primes, real_primes, 6));
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printf("%d\n", is_present(primes, real_primes, 13));
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return 0;
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}
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