Maximal Square

Author: nikoo28

src/main/java/leetcode/medium/MaximalSquare.java

@@ -0,0 +1,33 @@
+package leetcode.medium;
+
+public class MaximalSquare {
+
+  int maximalSquare(char[][] matrix) {
+
+    int rows = matrix.length;
+    int cols = matrix[0].length;
+    int[][] dp = new int[rows][cols];
+    int maxSide = 0;
+
+    // Fill the dp table
+    for (int i = 0; i < rows; i++) {
+      for (int j = 0; j < cols; j++) {
+        if (matrix[i][j] == '1') {
+
+          // Special handling for the first row and first column
+          if (i == 0 || j == 0)
+            dp[i][j] = 1;
+          else
+            // For others, dp[i][j] is the minimum of the three neighbors
+            dp[i][j] = Math.min(Math.min(dp[i-1][j], dp[i][j-1]), dp[i-1][j-1]) + 1;
+
+          maxSide = Math.max(maxSide, dp[i][j]);
+        }
+      }
+    }
+
+    // Return the area of the largest square
+    return maxSide * maxSide;
+  }
+
+}

src/test/java/leetcode/medium/MaximalSquareTest.java

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+package leetcode.medium;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class MaximalSquareTest {
+
+  private final MaximalSquare maximalSquare;
+
+  MaximalSquareTest() {
+    maximalSquare = new MaximalSquare();
+  }
+
+  @Test
+  void testMaximalSquare1() {
+    char[][] matrix = {
+      {'1', '0', '1', '0', '0'},
+      {'1', '0', '1', '1', '1'},
+      {'1', '1', '1', '1', '1'},
+      {'1', '0', '0', '1', '0'}
+    };
+    assertEquals(4, maximalSquare.maximalSquare(matrix));
+  }
+
+  @Test
+  void testMaximalSquare2() {
+    char[][] matrix = {
+      {'0', '1'},
+      {'1', '0'}
+    };
+    assertEquals(1, maximalSquare.maximalSquare(matrix));
+  }
+
+  @Test
+  void testMaximalSquare3() {
+    char[][] matrix = {
+      {'0', '0'},
+      {'0', '0'}
+    };
+    assertEquals(0, maximalSquare.maximalSquare(matrix));
+  }
+
+  @Test
+  void testMaximalSquare4() {
+    char[][] matrix = {
+      {'1', '1', '1', '1'},
+      {'1', '1', '1', '1'},
+      {'1', '1', '1', '1'},
+      {'0', '0', '0', '0'}
+    };
+    assertEquals(9, maximalSquare.maximalSquare(matrix));
+  }
+
+  @Test
+  void testMaximalSquare5() {
+    char[][] matrix = {
+        {'1', '1', '1', '1'},
+    };
+    assertEquals(1, maximalSquare.maximalSquare(matrix));
+  }
+}