Contiguous Array

Author: nikoo28

src/main/java/leetcode/medium/ContiguousArray.java

@@ -0,0 +1,39 @@
+package leetcode.medium;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ContiguousArray {
+
+  int findMaxLength(int[] nums) {
+
+    if (nums == null || nums.length == 0) { // Base Case
+      return 0;
+    }
+
+    // Converting all 0 to -1
+    for (int i = 0; i < nums.length; i++)
+      if (nums[i] == 0) nums[i] = -1;
+
+    int sum = 0; // current
+    int maxLength = 0; // final-ans
+
+    Map<Integer, Integer> map = new HashMap<>();
+    map.put(0, -1); // put sentinel value
+
+    for (int i = 0; i < nums.length; i++) {
+      sum += nums[i];
+
+      if (map.containsKey(sum)) {
+        // if present, update length
+        int last = map.get(sum);
+        maxLength = Math.max(maxLength, i - last);
+      } else
+        map.put(sum, i);
+
+    }
+
+    return maxLength;
+  }
+
+}

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

@@ -19,7 +19,8 @@ int maximalSquare(char[][] matrix) {
             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;
+            dp[i][j] = 1 +
+                Math.min(Math.min(dp[i-1][j], dp[i][j-1]), dp[i-1][j-1]);
 
           maxSide = Math.max(maxSide, dp[i][j]);
         }

src/test/java/leetcode/medium/ContiguousArrayTest.java

@@ -0,0 +1,38 @@
+package leetcode.medium;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ContiguousArrayTest {
+
+  private final ContiguousArray contiguousArray;
+
+  ContiguousArrayTest() {
+    contiguousArray = new ContiguousArray();
+  }
+
+  @Test
+  void testFindMaxLength1() {
+    int[] nums = {0, 1, 0, 1, 0, 1};
+    assertEquals(6, contiguousArray.findMaxLength(nums));
+  }
+
+  @Test
+  void testFindMaxLength2() {
+    int[] nums = {0};
+    assertEquals(0, contiguousArray.findMaxLength(nums));
+  }
+
+  @Test
+  void testFindMaxLength3() {
+    int[] nums = {0, 1};
+    assertEquals(2, contiguousArray.findMaxLength(nums));
+  }
+
+  @Test
+  void testFindMaxLength4() {
+    int[] nums = {0, 1, 1, 0, 1};
+    assertEquals(4, contiguousArray.findMaxLength(nums));
+  }
+}