mgrettondann/advent-of-code
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Optimize 2018 day 6 part 2.

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Basically tighten the search parameters.
This commit is contained in:
Matthew Gretton-Dann
2022-12-21 10:59:49 +00:00
parent db293409e4
commit 3c3a1edd61
1 changed files with 12 additions and 7 deletions
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19
2018/puzzle-06-02.cc
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@@ -4,6 +4,7 @@
#include <algorithm> #include <algorithm>
#include <cstdlib> #include <cstdlib>
#include <execution>
#include <iomanip> #include <iomanip>
#include <iostream> #include <iostream>
#include <map> #include <map>
@@ -53,6 +54,11 @@ auto main() -> int
Point max(0, 0); Point max(0, 0);
std::regex const re{"(\\d+), (\\d+)"}; std::regex const re{"(\\d+), (\\d+)"};
Int const safe_distance{10'000};
// At the edge of the grid (0,0) or (max,max) what is the largest possible sum of distances we
// could have.
Int edge_distance{0};
// Read data // Read data
while (std::getline(std::cin, line)) { while (std::getline(std::cin, line)) {
std::smatch m; std::smatch m;
@@ -62,18 +68,17 @@ auto main() -> int
} }
Point const pt(std::stoll(m.str(1)), std::stoll(m.str(2))); Point const pt(std::stoll(m.str(1)), std::stoll(m.str(2)));
point_map.insert({pt, 0}); point_map.insert({pt, 0});
edge_distance += pt.first + pt.second;
max.first = std::max(max.first, pt.first); max.first = std::max(max.first, pt.first);
max.second = std::max(max.second, pt.second); max.second = std::max(max.second, pt.second);
} }
// Examine each point within the grid. We go over the top just to be safe
Int const safe_distance{10'000};
Int region_size{0}; Int region_size{0};
for (Int x{max.first - safe_distance - 1}; x <= safe_distance + 1; ++x) { // Edge distance now becomes how far we have to go beyond the edge of the grid to ensure we count
if (x % 1000 == 0) { // all bits of the grid.
std::cout << "x: " << x << "\n"; edge_distance = (edge_distance > safe_distance) ? 0 : safe_distance - edge_distance;
} for (Int x{-edge_distance}; x <= max.first + edge_distance; ++x) {
for (Int y{max.second - safe_distance - 1}; y <= safe_distance + 1; ++y) { for (Int y{-edge_distance}; y <= max.second + edge_distance; ++y) {
if (within_distance(point_map.begin(), point_map.end(), Point(x, y), safe_distance)) { if (within_distance(point_map.begin(), point_map.end(), Point(x, y), safe_distance)) {
++region_size; ++region_size;
} }