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Author: whd

225 Implement Stack using Queues .cpp

@@ -0,0 +1,32 @@
+class Stack {
+public:
+    // Push element x onto stack.
+    void push(int x) {
+        while (!q.empty()) {
+            tmp.push(q.front());
+            q.pop();
+        }
+        q.push(x);
+        while (!tmp.empty()) {
+            q.push(tmp.front());
+            tmp.pop();
+        }
+    }
+
+    // Removes the element on top of the stack.
+    void pop() {
+        q.pop();
+    }
+
+    // Get the top element.
+    int top() {
+        return q.front();
+    }
+
+    // Return whether the stack is empty.
+    bool empty() {
+        return q.empty();
+    }
+private:
+    queue<int> q, tmp;
+};