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2022 day 15 part 2: improved solution (20,000 times faster)

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Bruno Raoult
2023-04-02 19:50:00 +02:00
parent 34b6cd7b57
commit 40a9c7b12e
1 changed files with 26 additions and 52 deletions
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78
2022/day15/aoc-c.c
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@@ -345,54 +345,6 @@ end:
return pair;
}
static ulong part1()
{
ulong res = 0;
int row = testmode() ? 10: 2000000;
uint bucket = hash_32(row, HBITS);
struct pair *pair;
map.min.y = map.max.y = row;
while ((pair = parse())) {
add_segments(pair);
}
struct row *prow = find_row(&map.hash[bucket], row);
if (prow) {
struct segment *cur;
list_for_each_entry(cur, &prow->segments, list) {
printf("counting segment (%d,%d) = %d nbeac=%d\n", cur->start, cur->end,
cur->end - cur->start + 1, prow->nbeacons);
res += cur->end - cur->start + 1;
}
res -= prow->nbeacons;
}
return res;
}
static ulong part2()
{
ulong res = 0;
struct pair *pair;
map.min.x = map.min.y = 0;
map.max.x = map.max.y = testmode()? 20: 4000000;
while ((pair = parse())) {
add_segments(pair);
}
for (int row = map.min.y; row <= map.max.y; ++row) {
uint bucket = hash_32(row, HBITS);
struct row *prow = find_row(&map.hash[bucket], row);
struct segment *cur;
cur = list_first_entry(&prow->segments, struct segment, list);
if (cur->end != map.max.x) {
res = ((u64)cur->end + 1UL) * 4000000UL + (u64)row;
break;
}
}
return res;
}
/**
* /#\
* /#\ /# #\
@@ -518,7 +470,32 @@ struct coord *check_intersect(struct coord *ret)
return NULL;
}
static ulong part2_new()
static ulong part1()
{
ulong res = 0;
int row = testmode() ? 10: 2000000;
uint bucket = hash_32(row, HBITS);
struct pair *pair;
map.min.y = map.max.y = row;
while ((pair = parse())) {
add_segments(pair);
}
struct row *prow = find_row(&map.hash[bucket], row);
if (prow) {
struct segment *cur;
list_for_each_entry(cur, &prow->segments, list) {
printf("counting segment (%d,%d) = %d nbeac=%d\n", cur->start, cur->end,
cur->end - cur->start + 1, prow->nbeacons);
res += cur->end - cur->start + 1;
}
res -= prow->nbeacons;
}
return res;
}
static ulong part2()
{
ulong res = 0;
struct coord result;
@@ -544,9 +521,6 @@ int main(int ac, char **av)
pool_segment = pool_create("segments", 8192, sizeof(struct segment));
pool_pair = pool_create("pair", 32, sizeof(struct pair));
//part2_new();
//printf("loops=%d\n", inner_count);
//exit(1);
printf("%s: res=%lu\n", *av, part == 1? part1(): part2());
printf("loops=%d\n", inner_count);
pool_destroy(pool_row);