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#include <math.h>
#include <stdlib.h>
#include <stdio.h>
void *emalloc(size_t s)
{
void *p = malloc(s);
if (p != NULL) return p;
fprintf(stderr, "Ran out of memory allocating a buffer of size %zu\n", s);
exit(EXIT_FAILURE);
}
long part1(long input)
{
long res = -1;
long *houses = emalloc(sizeof(long) * input / 10);
#pragma omp parallel for
for (long i = 1; i < input / 10; i++)
for (long j = i; j < input / 10; j += i)
houses[j] += i * 10;
for (long i = 1; i < input / 10; i++) {
if (houses[i] >= input) {
res = i;
break;
}
}
free(houses);
return res;
}
long part2(long input)
{
long res = -1;
long *houses = emalloc(sizeof(long) * input / 10);
#pragma omp parallel for
for (long i = 1; i < input / 10; i++)
for (long j = i, k = 0; j < input / 10 && k < 50; j += i, k++)
houses[j] += i * 11;
for (long i = 1; i < input / 10; i++) {
if (houses[i] >= input) {
res = i;
break;
}
}
free(houses);
return res;
}
int main(void)
{
long input = 33100000;
printf("%ld\n", part1(input));
printf("%ld\n", part2(input));
}
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