diff --git a/src/test/java/g0401_0500/s0441_arranging_coins/SolutionTest.java b/src/test/java/g0401_0500/s0441_arranging_coins/SolutionTest.java
index cffac2461..bdca1898d 100644
--- a/src/test/java/g0401_0500/s0441_arranging_coins/SolutionTest.java
+++ b/src/test/java/g0401_0500/s0441_arranging_coins/SolutionTest.java
@@ -2,6 +2,7 @@
 
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import org.junit.jupiter.api.Test;
 
@@ -15,4 +16,51 @@ void findKthNumber() {
     void arrangeCoins2() {
         assertThat(new Solution().arrangeCoins(8), equalTo(3));
     }
+
+    @Test
+    void arrangeCoins3() {
+        assertThat(new Solution().arrangeCoins(0), equalTo(0));
+    }
+
+    @Test
+    void arrangeCoins4() {
+        assertThat(new Solution().arrangeCoins(1), equalTo(1));
+    }
+
+    @Test
+    void arrangeCoins5() {
+        assertThat(new Solution().arrangeCoins(2), equalTo(1));
+    }
+
+    @Test
+    void arrangeCoins6() {
+        assertThat(new Solution().arrangeCoins(3), equalTo(2));
+    }
+
+    @Test
+    void arrangeCoins7() {
+        assertThat(new Solution().arrangeCoins(6), equalTo(3));
+    }
+
+    @Test
+    void arrangeCoins8() {
+        assertThat(new Solution().arrangeCoins(2147483647), equalTo(65535));
+    }
+
+    @Test
+    void arrangeCoins9() {
+        assertThat(new Solution().arrangeCoins(7), equalTo(3));
+    }
+
+    @Test
+    void arrangeCoins10() {
+        Solution solution = new Solution();
+
+        Exception exception =
+                assertThrows(IllegalArgumentException.class, () -> solution.arrangeCoins(-5));
+
+        assertThat(
+                exception.getMessage(),
+                equalTo("Input Number is invalid. Only positive numbers are allowed"));
+    }
 }
diff --git a/src/test/java/g0801_0900/s0836_rectangle_overlap/SolutionTest.java b/src/test/java/g0801_0900/s0836_rectangle_overlap/SolutionTest.java
index 48e7d22f8..617eafb6a 100644
--- a/src/test/java/g0801_0900/s0836_rectangle_overlap/SolutionTest.java
+++ b/src/test/java/g0801_0900/s0836_rectangle_overlap/SolutionTest.java
@@ -26,4 +26,47 @@ void isRectangleOverlap3() {
                 new Solution().isRectangleOverlap(new int[] {0, 0, 1, 1}, new int[] {2, 2, 3, 3}),
                 equalTo(false));
     }
+
+    @Test
+    void isRectangleOverlap4() {
+        assertThat(
+                new Solution().isRectangleOverlap(new int[] {0, 0, 2, 2}, new int[] {0, 2, 2, 4}),
+                equalTo(false));
+    }
+
+    @Test
+    void isRectangleOverlap5() {
+        assertThat(
+                new Solution().isRectangleOverlap(new int[] {1, 1, 3, 3}, new int[] {1, 0, 3, 1}),
+                equalTo(false));
+    }
+
+    @Test
+    void isRectangleOverlap6() {
+        assertThat(
+                new Solution()
+                        .isRectangleOverlap(new int[] {-3, -3, -1, -1}, new int[] {-2, -2, 0, 0}),
+                equalTo(true));
+    }
+
+    @Test
+    void isRectangleOverlap7() {
+        assertThat(
+                new Solution().isRectangleOverlap(new int[] {0, 0, 4, 4}, new int[] {1, 1, 3, 3}),
+                equalTo(true));
+    }
+
+    @Test
+    void isRectangleOverlap8() {
+        assertThat(
+                new Solution().isRectangleOverlap(new int[] {0, 0, 2, 2}, new int[] {0, 0, 2, 2}),
+                equalTo(true));
+    }
+
+    @Test
+    void isRectangleOverlap9() {
+        assertThat(
+                new Solution().isRectangleOverlap(new int[] {0, 0, 1, 1}, new int[] {1, 1, 2, 2}),
+                equalTo(false));
+    }
 }
diff --git a/src/test/java/g0801_0900/s0840_magic_squares_in_grid/SolutionTest.java b/src/test/java/g0801_0900/s0840_magic_squares_in_grid/SolutionTest.java
index b8d0dcd73..dfc7c1d31 100644
--- a/src/test/java/g0801_0900/s0840_magic_squares_in_grid/SolutionTest.java
+++ b/src/test/java/g0801_0900/s0840_magic_squares_in_grid/SolutionTest.java
@@ -19,4 +19,64 @@ void numMagicSquaresInside() {
     void numMagicSquaresInside2() {
         assertThat(new Solution().numMagicSquaresInside(new int[][] {{8}}), equalTo(0));
     }
+
+    @Test
+    void numMagicSquaresInside3() {
+        assertThat(new Solution().numMagicSquaresInside(new int[][] {{1, 2}, {3, 4}}), equalTo(0));
+    }
+
+    @Test
+    void numMagicSquaresInside4() {
+        assertThat(
+                new Solution()
+                        .numMagicSquaresInside(
+                                new int[][] {
+                                    {4, 3, 8, 4, 3},
+                                    {9, 5, 1, 9, 5},
+                                    {2, 7, 6, 2, 7},
+                                    {4, 3, 8, 4, 3},
+                                    {9, 5, 1, 9, 5}
+                                }),
+                equalTo(1));
+    }
+
+    @Test
+    void numMagicSquaresInside5() {
+        assertThat(
+                new Solution()
+                        .numMagicSquaresInside(
+                                new int[][] {
+                                    {10, 3, 8},
+                                    {9, 5, 1},
+                                    {2, 7, 6}
+                                }),
+                equalTo(0));
+    }
+
+    @Test
+    void numMagicSquaresInside6() {
+        assertThat(
+                new Solution()
+                        .numMagicSquaresInside(
+                                new int[][] {
+                                    {4, 3, 8, 4},
+                                    {9, 5, 1, 9},
+                                    {2, 7, 6, 2},
+                                    {4, 3, 8, 4}
+                                }),
+                equalTo(1));
+    }
+
+    @Test
+    void numMagicSquaresInside7() {
+        assertThat(
+                new Solution()
+                        .numMagicSquaresInside(
+                                new int[][] {
+                                    {2, 2, 2},
+                                    {2, 2, 2},
+                                    {2, 2, 2}
+                                }),
+                equalTo(0));
+    }
 }
diff --git a/src/test/java/g0801_0900/s0863_all_nodes_distance_k_in_binary_tree/SolutionTest.java b/src/test/java/g0801_0900/s0863_all_nodes_distance_k_in_binary_tree/SolutionTest.java
index 0ad390e13..7ab724137 100644
--- a/src/test/java/g0801_0900/s0863_all_nodes_distance_k_in_binary_tree/SolutionTest.java
+++ b/src/test/java/g0801_0900/s0863_all_nodes_distance_k_in_binary_tree/SolutionTest.java
@@ -32,4 +32,40 @@ void distanceK2() {
                                 3),
                 equalTo(Collections.emptyList()));
     }
+
+    @Test
+    void distanceK3() {
+        TreeNode root =
+                TreeUtils.constructBinaryTree(Arrays.asList(3, 5, 1, 6, 2, 0, 8, null, null, 7, 4));
+        assertThat(
+                new Solution().distanceK(root, new TreeNode(3), 2),
+                equalTo(Arrays.asList(6, 2, 0, 8)));
+    }
+
+    @Test
+    void distanceK4() {
+        TreeNode root =
+                TreeUtils.constructBinaryTree(Arrays.asList(3, 5, 1, 6, 2, 0, 8, null, null, 7, 4));
+        assertThat(new Solution().distanceK(root, new TreeNode(7), 1), equalTo(Arrays.asList(2)));
+    }
+
+    @Test
+    void distanceK5() {
+        TreeNode root = TreeUtils.constructBinaryTree(Arrays.asList(1, 2, 3));
+        assertThat(new Solution().distanceK(root, new TreeNode(2), 0), equalTo(Arrays.asList(2)));
+    }
+
+    @Test
+    void distanceK6() {
+        TreeNode root = TreeUtils.constructBinaryTree(Arrays.asList(1, 2, 3));
+        assertThat(
+                new Solution().distanceK(root, new TreeNode(1), 5),
+                equalTo(Collections.emptyList()));
+    }
+
+    @Test
+    void distanceK7() {
+        TreeNode root = TreeUtils.constructBinaryTree(Arrays.asList(1, 2, null, 3, null, 4));
+        assertThat(new Solution().distanceK(root, new TreeNode(2), 2), equalTo(Arrays.asList(4)));
+    }
 }
diff --git a/src/test/java/g3001_3100/s3040_maximum_number_of_operations_with_the_same_score_ii/SolutionTest.java b/src/test/java/g3001_3100/s3040_maximum_number_of_operations_with_the_same_score_ii/SolutionTest.java
index d4e9c939a..4120a1376 100644
--- a/src/test/java/g3001_3100/s3040_maximum_number_of_operations_with_the_same_score_ii/SolutionTest.java
+++ b/src/test/java/g3001_3100/s3040_maximum_number_of_operations_with_the_same_score_ii/SolutionTest.java
@@ -15,4 +15,44 @@ void maxOperations() {
     void maxOperations2() {
         assertThat(new Solution().maxOperations(new int[] {3, 2, 6, 1, 4}), equalTo(2));
     }
+
+    @Test
+    void maxOperations3() {
+        assertThat(new Solution().maxOperations(new int[] {1, 2}), equalTo(1));
+    }
+
+    @Test
+    void maxOperations4() {
+        assertThat(new Solution().maxOperations(new int[] {1, 1, 1}), equalTo(1));
+    }
+
+    @Test
+    void maxOperations5() {
+        assertThat(new Solution().maxOperations(new int[] {2, 2, 2, 2, 2, 2}), equalTo(3));
+    }
+
+    @Test
+    void maxOperations6() {
+        assertThat(new Solution().maxOperations(new int[] {1, 2, 3, 4, 5, 6}), equalTo(3));
+    }
+
+    @Test
+    void maxOperations7() {
+        assertThat(new Solution().maxOperations(new int[] {6, 5, 4, 3, 2, 1}), equalTo(3));
+    }
+
+    @Test
+    void maxOperations8() {
+        assertThat(new Solution().maxOperations(new int[] {1, 3, 2, 4, 1, 3}), equalTo(2));
+    }
+
+    @Test
+    void maxOperations9() {
+        assertThat(new Solution().maxOperations(new int[] {1, 2, 4, 5}), equalTo(2));
+    }
+
+    @Test
+    void maxOperations10() {
+        assertThat(new Solution().maxOperations(new int[] {5, 5}), equalTo(1));
+    }
 }