Puzzle game in cpp with comments and tests

bfs/puzzle_game/puzzle_game.cpp

@@ -0,0 +1,77 @@
+/*
+General solution: Each board gets mapped to an integer in the range [0, 9^9)
+We visualize the board as a 9 digit number written in base 9 and then convert it to base 10
+We then simply run a BFS trying to reach the end state 
+*/
+#include <bits/stdc++.h>
+
+using namespace std;
+
+const int N = 381367045;
+
+// A bitset to check visited states
+bitset<N> vis;
+// Precomputate the powers of 9
+int pwr[10], dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1};
+map<int, bool> primes = {{2, true}, {3, true}, {5, true}, {7, true}, {11, true}, {13, true}, {17, true}};
+
+int mapping(vector<vector<int>> &v) {
+    int x = 0;
+    for (int i = 2; i >= 0; i--) {
+        for (int j = 2; j >= 0; j--) {
+            x = 9 * x + v[i][j] % 9;
+        }
+    }
+    return x;
+}
+
+int main () { 
+    vector<vector<int>> v = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
+    int goal = mapping(v);
+    int t;
+    cin >> t;
+    while (t--) {
+        for (int i = 0; i < 3; i++) {
+            for (int j = 0; j < 3; j++) {
+                cin >> v[i][j];
+            }
+        }
+        queue<pair<vector<vector<int>>, int>> q;
+        q.push({v, 0});
+        int mp = mapping(v);
+        vis[mp] = true;
+        vector<int> visited_states = {mp};
+        while (!q.empty()) {
+            v = q.front().first;
+            int dist = q.front().second;
+            q.pop();
+            if (mapping(v) == goal) {
+                cout << dist << '\n';
+                break;
+            }
+            for (int x = 0; x < 3; x++) {
+                for (int y = 0; y < 3; y++) {
+                    for (int i = 0; i < 4; i++) {
+                        int nx = x + dx[i], ny = y + dy[i];
+                        if (nx >= 0 && nx < 3 && ny >= 0 && ny < 3 && primes[v[x][y] + v[nx][ny]]) {
+                            swap(v[x][y], v[nx][ny]);
+                            int mp = mapping(v);
+                            if (!vis[mp]) {
+                                vis[mp] = true;
+                                visited_states.push_back(mp);
+                                q.push({v, dist + 1});
+                            }
+                            swap(v[x][y], v[nx][ny]);
+                        }
+                    }
+                }
+            }
+        }
+        if (!vis[goal]) cout << "-1\n";
+        // resetting our bitset for the next test case
+        for (int x : visited_states) {
+            vis[x] = false;
+        }
+    }
+    return 0;
+}

bfs/puzzle_game/tests/t1.in

@@ -0,0 +1,9 @@
+2
+
+5 9 1
+2 8 4
+3 6 7
+
+9 8 7
+6 5 4
+3 2 1

bfs/puzzle_game/tests/t1.out

@@ -0,0 +1,2 @@
+-1
+48

bfs/puzzle_game/tests/t2.in

@@ -0,0 +1,13 @@
+3
+
+1 9 2
+8 3 7
+4 6 5
+
+4 5 6
+1 2 3
+7 8 9
+
+7 8 9
+1 2 3
+4 5 6

bfs/puzzle_game/tests/t2.out

@@ -0,0 +1,3 @@
+52
+21
+-1

bfs/puzzle_game/tests/t3.in

@@ -0,0 +1,13 @@
+3
+
+4 1 2
+9 3 5
+6 7 8
+
+4 3 2
+7 6 5
+1 9 8
+
+9 5 1
+2 8 7
+6 4 3

bfs/puzzle_game/tests/t3.out

@@ -0,0 +1,3 @@
+24
+-1
+44