Design-2

Sample.java

@@ -1,7 +1,60 @@
-// Time Complexity :
-// Space Complexity :
-// Did this code successfully run on Leetcode :
-// Any problem you faced while coding this :
+// Time Complexity : O(1) amortized for push, pop, peek
+// Space Complexity : O(n) where n is the number of elements in the queue
+// Did this code successfully run on Leetcode : yes
+// Any problem you faced while coding this :  No
 
 
 // Your code here along with comments explaining your approach
+
+I created two stacks and
+used one staack for pushing and other for poping and peeking.
+When pop or peek is called, I checked if the outStack is empty.If it is empty, I transferred all elements from inStack to outStack.
+
+class MyQueue {
+    private Stack<Integer> inStack;
+    private Stack<Integer> outStack;
+
+    public MyQueue() {
+        inStack= new Stack<Integer>();
+        outStack= new Stack<Integer>();
+    }
+
+    public void push(int x) {
+        inStack.push(x);
+
+    }
+
+    public int pop() {
+        if(outStack.isEmpty()){
+            while(!inStack.isEmpty()){
+                outStack.push(inStack.pop());
+            }
+        }
+        return outStack.pop();
+    }
+
+    public int peek() {
+        if(outStack.isEmpty()){
+            while(!inStack.isEmpty()){
+                outStack.push(inStack.pop());
+            }
+        }
+        return outStack.peek();
+    }
+
+    public boolean empty() {
+        if(outStack.isEmpty()&&inStack.isEmpty()){
+            return true;
+        }
+        return false;
+    }
+}
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * MyQueue obj = new MyQueue();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.peek();
+ * boolean param_4 = obj.empty();
+ */