@@ -4,6 +4,8 @@ namespace Solutions.Tests.Problems;
 
 public class CarFleetTest
 {
+    public CarFleetSolution Solution { get; set; } = new();
+
     [Fact]
     public void Case1()
     {
@@ -13,8 +15,8 @@ public void Case1()
         int target = 12;
 
         // Act
-        int result = new CarFleetSolution().CarFleet(target, positions, speed);
-        int resultIterator = new CarFleetSolution().CarFleetIterator(target, positions, speed);
+        int result = Solution.CarFleet(target, positions, speed);
+        int resultIterator = Solution.CarFleetIterator(target, positions, speed);
 
         // Assert
         Assert.Equal(3, result);
@@ -30,7 +32,7 @@ public void Case3()
         int target = 100;
 
         // Act
-        int result = new CarFleetSolution().CarFleet(target, positions, speed);
+        int result = Solution.CarFleet(target, positions, speed);
 
         // Assert
         Assert.Equal(1, result);
@@ -45,7 +47,7 @@ public void Case4()
         int target = 10;
 
         // Act
-        int result = new CarFleetSolution().CarFleet(target, positions, speed);
+        int result = Solution.CarFleet(target, positions, speed);
 
         // Assert
         Assert.Equal(2, result);
 
@@ -4,15 +4,17 @@ namespace Solutions.Tests.Problems;
 
 public class ContainsDuplicateTest
 {
+    public ContainsDuplicateSolution Solution { get; set; } = new();
+
     [Fact]
     public void Case1()
     {
         // Arrange
         int[] nums = [1, 2, 3, 1];
 
         // Act
-        bool result = new ContainsDuplicateSolution().ContainsDuplicate(nums);
-        bool resultSort = new ContainsDuplicateSolution().ContainsDuplicateSorting(nums);
+        bool result = Solution.ContainsDuplicate(nums);
+        bool resultSort = Solution.ContainsDuplicateSorting(nums);
 
         // Assert
         Assert.True(result);
@@ -26,7 +28,7 @@ public void Case2()
         int[] nums = [1, 2, 3, 4];
 
         // Act
-        bool result = new ContainsDuplicateSolution().ContainsDuplicate(nums);
+        bool result = Solution.ContainsDuplicate(nums);
 
         // Assert
         Assert.False(result);
@@ -39,7 +41,7 @@ public void Case3()
         int[] nums = [1, 1, 1, 3, 3, 4, 3, 2, 4, 2];
 
         // Act
-        bool result = new ContainsDuplicateSolution().ContainsDuplicate(nums);
+        bool result = Solution.ContainsDuplicate(nums);
 
         // Assert
         Assert.True(result);
 
@@ -5,6 +5,8 @@ namespace Solutions.Tests.Problems;
 
 public class InvertBinaryTreeTest
 {
+    public InvertBinaryTreeSolution Solution { get; set; } = new();
+
     [Fact]
     public void Case1()
     {
@@ -13,7 +15,7 @@ public void Case1()
         TreeNode? treeNode = TreeNode.FromArrayIterative(tree);
 
         // Act
-        TreeNode? result = new InvertBinaryTreeSolution().InvertTree(treeNode);
+        TreeNode? result = Solution.InvertTree(treeNode);
         int[] resultArray = TreeNode.ToArray(result);
 
         // Assert
@@ -28,7 +30,7 @@ public void Case2()
         TreeNode? treeNode = TreeNode.FromArray(tree);
 
         // Act
-        TreeNode? result = new InvertBinaryTreeSolution().InvertTree(treeNode);
+        TreeNode? result = Solution.InvertTree(treeNode);
         int[] resultArray = TreeNode.ToArray(result);
 
         // Assert
@@ -43,7 +45,7 @@ public void Case3()
         TreeNode? treeNode = TreeNode.FromArray(tree);
 
         // Act
-        TreeNode? result = new InvertBinaryTreeSolution().InvertTree(treeNode);
+        TreeNode? result = Solution.InvertTree(treeNode);
         int[] resultArray = TreeNode.ToArray(result);
 
         // Assert