RosettaCodeData/Task/Hamming-numbers/C/hamming-numbers-1.c
2023-07-01 13:44:08 -04:00

56 lines
921 B
C

#include <stdio.h>
#include <stdlib.h>
typedef unsigned long long ham;
size_t alloc = 0, n = 1;
ham *q = 0;
void qpush(ham h)
{
int i, j;
if (alloc <= n) {
alloc = alloc ? alloc * 2 : 16;
q = realloc(q, sizeof(ham) * alloc);
}
for (i = n++; (j = i/2) && q[j] > h; q[i] = q[j], i = j);
q[i] = h;
}
ham qpop()
{
int i, j;
ham r, t;
/* outer loop for skipping duplicates */
for (r = q[1]; n > 1 && r == q[1]; q[i] = t) {
/* inner loop is the normal down heap routine */
for (i = 1, t = q[--n]; (j = i * 2) < n;) {
if (j + 1 < n && q[j] > q[j+1]) j++;
if (t <= q[j]) break;
q[i] = q[j], i = j;
}
}
return r;
}
int main()
{
int i;
ham h;
for (qpush(i = 1); i <= 1691; i++) {
/* takes smallest value, and queue its multiples */
h = qpop();
qpush(h * 2);
qpush(h * 3);
qpush(h * 5);
if (i <= 20 || i == 1691)
printf("%6d: %llu\n", i, h);
}
/* free(q); */
return 0;
}