Implement min Stack using another stack

Author: apurva313

Diff for: Stack/MinStack.java

@@ -0,0 +1,58 @@
+import java.util.Stack;
+
+class MinStack {
+    Stack<Integer> st = new Stack<>();
+    Stack<Integer> min = new Stack<>();
+
+    public MinStack() {}
+
+    public void push(int val) {
+        st.push(val);
+        if (min.isEmpty() || val <= min.peek()) {
+            min.push(val);
+        } else {
+            min.push(min.peek());
+        }
+    }
+
+    public void pop() {
+        st.pop();
+        min.pop();
+    }
+
+    public int top() {
+        return st.peek();
+    }
+
+    public int getMin() {
+        return min.peek();
+    }
+
+    public static void main(String[] args) {
+        MinStack obj = new MinStack();
+        obj.push(5);
+        System.out.println("Pushed 5");
+        System.out.println("Top element: " + obj.top());
+        System.out.println("Minimum element: " + obj.getMin());
+
+        obj.push(3);
+        System.out.println("Pushed 3");
+        System.out.println("Top element: " + obj.top());
+        System.out.println("Minimum element: " + obj.getMin());
+
+        obj.push(7);
+        System.out.println("Pushed 7");
+        System.out.println("Top element: " + obj.top());
+        System.out.println("Minimum element: " + obj.getMin());
+
+        obj.push(2);
+        System.out.println("Pushed 2");
+        System.out.println("Top element: " + obj.top());
+        System.out.println("Minimum element: " + obj.getMin());
+
+        obj.pop();
+        System.out.println("Popped");
+        System.out.println("Top element: " + obj.top());
+        System.out.println("Minimum element: " + obj.getMin());
+    }
+}