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if (*data) {
for (int k = 0; k < *data - '0'; k++) {
if (ndisk == rdisk) {
// assume it works
rdisk = (13*rdisk)/8;
disk = realloc(disk, rdisk * sizeof *disk);
}
disk[ndisk++] = -1;
}
data++;
}
}
int *left = disk, *right = disk + ndisk;
for (;;) {
while (*left != -1) left++;
if (left >= right) break;
while (right[-1] == -1) right--;
// swap *left and right[-1]
int tmp = *--right;
*right = *left;
*left++ = tmp;
}
unsigned long long chksum = 0;
size_t index = 0;
while (disk[index] >= 0) {
chksum += (size_t)disk[index] * index;
index++;
}
printf("%llu\n", chksum);
free(disk);
}
/* === aoc202408 =======================================================
Oh! another square of text!
Idea: for all points p with an antenna find all points q>p with
a corresponding frequency. For each such pair calculate the 2 antinodes
and add the resulting points (if not there already) to an array.
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if (*data) {
for (int k = 0; k < *data - '0'; k++) {
if (ndisk == rdisk) {
// assume it works
rdisk = (13*rdisk)/8;
disk = realloc(disk, rdisk * sizeof *disk);
}
disk[ndisk++] = -1 * (*data - '0');
}
data++;
}
}
// copy disk
int *diskcopy = malloc(ndisk * sizeof *disk);
memcpy(diskcopy, disk, ndisk * sizeof *disk);
int *left = disk, *right = disk + ndisk;
for (;;) {
while (*left >= 0) left++;
if (left >= right) break;
while (right[-1] < 0) right--;
// swap *left and right[-1]
int tmp = *--right;
*right = *left;
*left++ = tmp;
}
unsigned long long chksum = 0;
size_t index = 0;
while (disk[index] >= 0) {
chksum += (size_t)disk[index] * index;
index++;
}
printf("%llu\n", chksum);
free(disk);
// part 2
free(diskcopy);
}
/* === aoc202408 =======================================================
Oh! another square of text!
Idea: for all points p with an antenna find all points q>p with
a corresponding frequency. For each such pair calculate the 2 antinodes
and add the resulting points (if not there already) to an array.
|