add queue use stack

Author: tg123

implement-queue-using-stacks/README.md

@@ -0,0 +1,35 @@
+class MyQueue {
+
+    // should use Deque<Integer> stack in modern java
+    Stack<Integer> stack = new Stack<>();
+
+    // Push element x to the back of queue.
+    public void push(int x) {
+        Stack<Integer> rev = new Stack<>();
+
+        while(!stack.empty()){
+            rev.push(stack.pop());
+        }
+        
+        rev.push(x);
+
+        while(!rev.empty()){
+            stack.push(rev.pop());
+        }
+    }
+
+    // Removes the element from in front of queue.
+    public void pop() {
+        stack.pop();
+    }
+
+    // Get the front element.
+    public int peek() {
+        return stack.peek();
+    }
+
+    // Return whether the queue is empty.
+    public boolean empty() {
+        return stack.empty();
+    }
+}

implement-queue-using-stacks/Solution.java

@@ -0,0 +1,7 @@
+---
+layout: solution
+title: Implement Queue using Stacks
+date: 2015-07-07 21:04:46+08:00
+leetcode_id: 232
+---
+{% include_relative README.md %}