MinesweeperMacaw solved

solutions/practice/MinesweeperMacaw.java

@@ -0,0 +1,115 @@
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Scanner;
+
+public class MinesweeperMacaw {
+  public static char[][] grid;
+  public static char[][] modGrid;
+  public static int unknowns = 0;
+  public static boolean solved = false;
+  public static HashMap<Integer, ArrayList<Integer>> unknownLocations = new HashMap<>();
+
+  public static void main(String[] args) {
+    Scanner sc = new Scanner(System.in);
+    int size = sc.nextInt();
+    int macaws = sc.nextInt();
+    grid = new char[size][size];
+
+    for (int i = 0; i < grid.length; i++) {
+
+      for (int j = 0; j < grid.length; j++) {
+        grid[i][j] = sc.next().charAt(0);
+        if (grid[i][j] == '.') {
+          ArrayList<Integer> l = new ArrayList<>();
+          l.add(i);
+          l.add(j);
+          unknownLocations.put(unknowns, l);
+          unknowns++;
+        }
+      }
+    }
+    modGrid = new char[size][size];
+    for (int i = 0; i < size; i++) {
+      modGrid[i] = grid[i].clone();
+    }
+
+    if (unknowns != 0) {
+      placeMacaws(0, macaws);
+    }
+
+    printGrid(grid);
+
+    sc.close();
+
+  }
+
+  public static void placeMacaws(int index, int macawsLeft) {
+    if (macawsLeft == 0) {
+      if (valid(modGrid)) {
+        for (int i = 0; i < modGrid.length; i++) {
+          grid[i] = modGrid[i].clone();
+        }
+        solved = true;
+      }
+      return;
+    }
+
+    if (solved)
+      return;
+
+    if (index == unknowns) {
+      return;
+    }
+
+    int a = unknownLocations.get(index).get(0);
+    int b = unknownLocations.get(index).get(1);
+
+    modGrid[a][b] = 'M';
+    placeMacaws(index + 1, macawsLeft - 1);
+
+    modGrid[a][b] = '.';
+    placeMacaws(index + 1, macawsLeft);
+
+  }
+
+  public static boolean valid(char[][] input) {
+    for (int i = 0; i < input.length; i++) {
+      for (int j = 0; j < input[i].length; j++) {
+        char c = input[i][j];
+        if (Character.isDigit(c)) {
+          int val = c - '0';
+          int num = 0;
+
+          for (int m = -1; m < 2; m++) {
+            for (int n = -1; n < 2; n++) {
+              if (i + m >= 0 && i + m < input.length && j + n >= 0 && j + n < input[0].length) {
+                if (input[i + m][j + n] == 'M') {
+                  num++;
+                }
+              }
+            }
+          }
+
+          if (num != val) {
+            return false;
+          }
+        }
+      }
+    }
+
+    return true;
+  }
+
+  public static void printGrid(char[][] input) {
+    for (int i = 0; i < input.length; i++) {
+      String out = "";
+      for (int j = 0; j < input[i].length - 1; j++) {
+        out = out + input[i][j];
+        out += " ";
+      }
+      out += input[i][input[i].length - 1];
+      System.out.println(out);
+    }
+  }
+}