feat: Add MinStackUsingTwoStacks new algorithm with Junit tests (#5758)

src/test/java/com/thealgorithms/stacks/MinStackUsingTwoStacksTest.java

@@ -0,0 +1,38 @@
+package com.thealgorithms.stacks;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class MinStackUsingTwoStacksTest {
+
+    @Test
+    public void testMinStackOperations() {
+        MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks();
+        minStack.push(3);
+        minStack.push(5);
+        assertEquals(3, minStack.getMin());
+
+        minStack.push(2);
+        minStack.push(1);
+        assertEquals(1, minStack.getMin());
+
+        minStack.pop();
+        assertEquals(2, minStack.getMin());
+    }
+
+    @Test
+    public void testMinStackOperations2() {
+        MinStackUsingTwoStacks minStack = new MinStackUsingTwoStacks();
+        minStack.push(3);
+        minStack.push(5);
+        assertEquals(3, minStack.getMin());
+
+        minStack.push(2);
+        minStack.push(1);
+        assertEquals(1, minStack.getMin());
+
+        minStack.pop();
+        assertEquals(2, minStack.getMin());
+    }
+}