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Author: MathProgrammer

2021/Div 2/724/Programs/Omkar and Forest.cpp

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+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+long long power_mod(long long x, long long power, long long mod)
+{
+    long long result = 1;
+
+    while(power)
+    {
+        if(power%2 == 1)
+            result = (result*x)%mod;
+
+        x = (x*x)%mod;
+        power = power >> 1;
+    }
+
+    return result;
+}
+
+void solve()
+{
+    int rows, columns;
+    cin >> rows >> columns;
+
+    vector <string> grid(rows);
+    for(int i = 0; i < rows; i++)
+    {
+        cin >> grid[i];
+    }
+
+    const char FREE_SPACE = '#';
+    int free_spaces = 0;
+    for(int r = 0; r < rows; r++)
+    {
+        for(int c = 0; c < columns; c++)
+        {
+            free_spaces += (grid[r][c] == FREE_SPACE);
+        }
+    }
+
+    const int MOD = 1e9 + 7;
+    long long answer = power_mod(2, free_spaces, MOD);
+
+    if(free_spaces == rows*columns)
+    {
+        answer = (answer + MOD - 1)%MOD;
+    }
+
+    cout << answer << "\n";
+}
+
+int main()
+{
+    int no_of_test_cases;
+    cin >> no_of_test_cases;
+
+    while(no_of_test_cases--)
+        solve();
+
+    return 0;
+}
+