contests/advent_of_code/2022/8/main.cpp

#include <bits/stdc++.h>

using namespace std;

int WIDTH, HEIGHT;

int scenic_score(int i, int j, const vector<vector<int>>& tree_height_map){
    int left = 0, right = 0, up = 0, down = 0;
    int tree_height = tree_height_map[i][j];

    // Look to the right
    for(int x = j + 1; x < WIDTH; ++x){
        if(tree_height_map[i][x] >= tree_height){
            right++;
            break;
        }
        right++;
    }

    // Look to the left
    for(int x = j - 1; x >= 0; --x){
        if(tree_height_map[i][x] >= tree_height){
            left++;
            break;
        }
        left++;
    }

    // Look down
    for(int y = i + 1; y < HEIGHT; ++y){
        if(tree_height_map[y][j] >= tree_height){
            down++;
            break;
        }
        down++;
    }

    // Look up
    for(int y = i - 1; y >= 0; --y){
        if(tree_height_map[y][j] >= tree_height){
            up++;
            break;
        }
        up++;
    }

    return left * right * up * down;
}

int main(){
    ifstream input_file("input.txt");
    string line;

    vector<vector<int>> tree_height_map;
    
    while(getline(input_file, line)){
        vector<int> acc;
        for(char c : line){
            acc.push_back(c - '0');
        }
        tree_height_map.push_back(acc);
    }

    WIDTH = tree_height_map.at(0).size();
    HEIGHT = tree_height_map.size();

    vector<vector<bool>> spotted_trees;
    vector<bool> dummy(WIDTH, false);
    for(int i = 0; i < HEIGHT; ++i){
        spotted_trees.push_back(dummy);
    }

    int result = 0;
    // Now check from all directions
    // Left to right first
    for(int i = 0; i < HEIGHT; ++i){
        int highest_tree = -1;

        for(int j = 0; j < WIDTH; ++j){
            if(tree_height_map[i][j] > highest_tree){
                highest_tree = tree_height_map[i][j];

                if(!spotted_trees[i][j]){
                    result++;
                    spotted_trees[i][j] = true;
                }
            }
        }
    }

    // From right to left
    for(int i = 0; i < HEIGHT; ++i){
        int highest_tree = -1;

        for(int j = WIDTH; j > 0; --j){
            if(tree_height_map[i][j-1] > highest_tree){
                highest_tree = tree_height_map[i][j-1];

                if(!spotted_trees[i][j-1]){
                    result++;
                    spotted_trees[i][j-1] = true;
                }
            }
        }
    }

    // From top to bottom
    for(int j = 0; j < WIDTH; ++j){
        int highest_tree = -1;

        for(int i = 0; i < HEIGHT; ++i){
            if(tree_height_map[i][j] > highest_tree){
                highest_tree = tree_height_map[i][j];

                if(!spotted_trees[i][j]){
                    result++;
                    spotted_trees[i][j] = true;
                }
            }
        }
    }

    // From bottom to top
    for(int j = 0; j < WIDTH; ++j){
        int highest_tree = -1;
        
        for(int i = HEIGHT; i > 0; --i){
            if(tree_height_map[i-1][j] > highest_tree){
                highest_tree = tree_height_map[i-1][j];

                if(!spotted_trees[i-1][j]){
                    result++;
                    spotted_trees[i-1][j] = true;
                }
            }
        }
    }

    cout << "Number of spotted trees: " << result << endl;

    // For part 2, let's try checking all hidden trees on their viewing distances
    // and see if we're not too slow with such a brute force

    int max_scenic_score = 0;
    for(int i = 0; i < HEIGHT; ++i){
        for(int j = 0; j < WIDTH; ++j){
            if(spotted_trees[i][j]){
                max_scenic_score = max(max_scenic_score, scenic_score(i, j, tree_height_map));
            }
        }
    }
    cout << "Maximal scenic score: " << max_scenic_score << endl;

    return 0;
}