advent_of_code/2022/08/main.cpp

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2022-12-08 05:30:48 +00:00
#include <cstddef>
#include <fstream>
#include <iostream>
#include <sstream>
#include <vector>
std::vector<std::vector<int>> getTrees( std::ifstream &file ) {
std::vector<std::vector<int>> ret{};
std::string str;
while ( std::getline( file, str ) ) {
ret.emplace_back();
for(auto &tree : str) {
ret.back().push_back(tree - '0');
}
}
return ret;
}
std::vector<std::vector<int>> getVisibilities(const std::vector<std::vector<int>> &trees) {
std::vector<std::vector<int>> visibilities;
visibilities.resize(trees.size());
for(auto &line : visibilities) {
line.resize(trees[0].size());
}
for(size_t i = 0; i < trees.size(); i++) {
int max_left = -1;
int max_right = -1;
for(size_t j = 0; j < trees[i].size(); j++) {
auto right_index = trees[0].size() - 1 - j;
// left
if(trees[i][j] > max_left) {
max_left = trees[i][j];
visibilities[i][j] += 1;
}
// right
if(trees[i][right_index] > max_right) {
max_right = trees[i][right_index];
visibilities[i][right_index] += 1;
}
}
}
for(size_t i = 0; i < trees[0].size(); i++) {
int max_top = -1;
int max_bottom = -1;
for(size_t j = 0; j < trees.size(); j++) {
auto bottom_index = trees.size() - 1 - j;
// top
if(trees[j][i] > max_top) {
max_top = trees[j][i];
visibilities[j][i] += 1;
}
// bottom
if(trees[bottom_index][i] > max_bottom) {
max_bottom = trees[bottom_index][i];
visibilities[bottom_index][i] += 1;
}
}
}
return visibilities;
}
int part1(const std::vector<std::vector<int>> &trees) {
auto visibilities = getVisibilities(trees);
int visible_trees = 0;
for(auto &line : visibilities) {
for(auto &tree : line) {
if(tree > 0) {
visible_trees++;
}
}
}
return visible_trees;
}
int getTreeScore(const std::vector<std::vector<int>> &trees, int y, int x) {
const auto max_height = trees[y][x];
int top = 0;
int left = 0;
int down = 0;
int right = 0;
// top
for(int i = y-1; i >= 0; i--) {
top++;
if(trees[i][x] >= max_height) {
break;
}
}
// left
for(int i = x-1; i >= 0; i--) {
left++;
if(trees[y][i] >= max_height) {
break;
}
}
// down
for(int i = y+1; i < (int)trees.size(); i++) {
down++;
if(trees[i][x] >= max_height) {
break;
}
}
// right
for(int i = x+1; i < (int)trees[0].size(); i++) {
right++;
if(trees[y][i] >= max_height) {
break;
}
}
return top * left * down * right;
}
int part2(const std::vector<std::vector<int>> &trees) {
int max_score = 0;
for(int i = 0; i < (int)trees.size(); i++) {
for(int j = 0; j < (int)trees[0].size(); j++) {
auto score = getTreeScore(trees, i, j);
if(score > max_score) {
max_score = score;
}
}
}
return max_score;
}
int main() {
std::ifstream input_file( "input" );
auto trees = getTrees( input_file );
part1(trees);
std::cout << "There are \033[91;1m" << part1(trees)
<< "\033[0m trees visible from the outside." << std::endl;
std::cout << "The best tree in the forest has score \033[91;1m" << part2(trees)
<< "\033[0m." << std::endl;
}