added day 12

day 12/day_12_felix.cpp

+#include <bits/stdc++.h>
+using namespace std;
+const bool DEBUG = false;
+
+#define coord pair <int, int>
+#define ll long long
+
+const int MAX_SIZE = 200;
+# define boolarray array <array <bool, MAX_SIZE>, MAX_SIZE>
+
+const array <coord, 4> dirs = {coord(0, 1), coord(1, 0), coord(0, -1), coord(-1, 0)};
+const vector<vector<coord>> orth = {
+    {coord(1, 0), coord(-1, 0)},
+    {coord(0, 1), coord(0, -1)},
+    {coord(1, 0), coord(-1, 0)},
+    {coord(0, 1), coord(0, -1)}
+};
+
+boolarray visited = {false};
+vector<string> garden;
+
+struct regionInfo{
+    ll area = 0;
+    ll perimiter = 0;
+    ll sides = 0;
+};
+
+void read_input() {
+    string line;
+    while (getline(cin, line)) {
+        garden.push_back(line);
+    }
+}
+
+bool is_in_bounds(coord pos) {
+    return pos.first >= 0 && pos.first < garden.size() && pos.second >= 0 && pos.second < garden[0].size();
+}
+
+void tag_adjacent(coord pos,  boolarray &is_perimiter, boolarray &is_counted, int i) {
+    deque <coord> q;
+    q.push_back(pos);
+    while (!q.empty()) {
+        coord cur = q.front();
+        q.pop_front();
+        is_counted[cur.first+2][cur.second+2] = true;
+        DEBUG && cout << "     Checking " << cur.first << " " << cur.second << endl;
+        for (coord dir : orth[i]) {
+            coord next = coord(cur.first + dir.first, cur.second + dir.second);
+            DEBUG && cout << "       Next " << next.first << " " << next.second;
+            DEBUG && cout << " is perimiter " << is_perimiter[next.first+2][next.second+2];
+            DEBUG && cout << " is counted " << is_counted[next.first+2][next.second+2] << endl;
+            if (is_perimiter[next.first+2][next.second+2] && !is_counted[next.first+2][next.second+2]) {
+                q.push_back(next);
+            }
+        }
+    }
+}
+
+ll count_sides(vector<vector<coord>> side_pieces) {
+    DEBUG && cout << " Counting sides." << endl;
+    ll sides = 0;
+    for (int i = 0; i < 4; i++) {
+        boolarray is_perimiter = {false};
+        boolarray is_counted = {false};
+        for (coord pos : side_pieces[i]) {
+            is_perimiter[pos.first+2][pos.second+2] = true;
+        }
+        for (coord pos : side_pieces[i]) if (!is_counted[pos.first+2][pos.second+2]) {
+            sides++;
+            DEBUG && cout << "   Side at " << pos.first << " " << pos.second << " with direction " << i << endl;
+            tag_adjacent(pos, is_perimiter, is_counted, i);
+        }
+    }
+    return sides;
+}
+
+regionInfo calculate_region(coord starting_pos) {
+    ll area = 0;
+    ll perimeter = 0;
+    
+    deque <coord> q;
+    q.push_back(starting_pos);
+    
+    char c = garden[starting_pos.first][starting_pos.second];
+    
+    vector<vector<coord>> side_pieces = {{}, {}, {}, {}};
+
+    DEBUG && cout << "---------------------------------------" << endl;
+    DEBUG && cout << "Starting region " << c << " at " << starting_pos.first << " " << starting_pos.second << endl;
+    while (!q.empty()) {
+        coord cur = q.front();
+        q.pop_front();
+        
+        if (visited[cur.first][cur.second]) continue;
+        
+        visited[cur.first][cur.second] = true;
+        area++;
+        
+        DEBUG && cout << " Adding " << cur.first << " " << cur.second << endl;
+        for (int i = 0; i < 4; i++) {
+            coord dir = dirs[i];
+            coord next = coord(cur.first + dir.first, cur.second + dir.second);
+            if (is_in_bounds(next) && garden[next.first][next.second] == c) {
+                q.push_back(next);
+            } else {
+                perimeter++;
+                side_pieces[i].push_back(cur);
+            }
+        }
+    }
+    ll sides = count_sides(side_pieces);
+    DEBUG && cout << "Region " << c << " with area " << area << ", sides " << sides << " and perimeter " << perimeter << endl;
+    regionInfo res = {area, perimeter, sides};
+    return res;
+}
+
+pair<ll,ll> solve() {
+    ll part1 = 0;
+    ll part2 = 0;
+    for (int i = 0; i < garden.size(); i++) for (int j = 0; j < garden[i].size(); j++) {
+        if (visited[i][j]) continue;
+        regionInfo info = calculate_region(coord(i, j));
+        part1 += info.area * info.perimiter;
+        part2 += info.area * info.sides;
+    }
+    return {part1, part2};
+}
+
+int main () {
+    read_input();
+    pair<ll,ll> res = solve();
+    cout << "Part 1: " << res.first << endl;
+    cout << "Part 2: " << res.second << endl;
+
+    return 0;
+}
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