add: 220505 [cpp]

cpp/2205/220505.cpp

@@ -0,0 +1,64 @@
+#include <queue>
+#include <iostream>
+
+/**
+ * 225. Implement Stack using Queues
+ * Implement a last-in-first-out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal stack (push, top, pop, and empty).
+ *
+ * Implement the MyStack class:
+ *
+ * void push(int x) Pushes element x to the top of the stack.
+ * int pop() Removes the element on the top of the stack and returns it.
+ * int top() Returns the element on the top of the stack.
+ * boolean empty() Returns true if the stack is empty, false otherwise.
+ *
+ * Notes:
+ *
+ * You must use only standard operations of a queue, which means that only push to back, peek/pop from front, size and is empty operations are valid.
+ * Depending on your language, the queue may not be supported natively. You may simulate a queue using a list or deque (double-ended queue) as long as you use only a queue's standard operations.
+ */
+
+class MyStack {
+private:
+	std::queue<int> q;
+public:
+	MyStack() = default;
+
+	void push(int x) {
+		auto s = q.size();
+		q.push(x);
+		// It sucks.
+		// It is ugly, inefficient, slow, and horrible.
+		while (s--) {
+			q.push(q.front());
+			q.pop();
+		}
+	}
+
+	int pop() {
+		int ret = q.front();
+		q.pop();
+		return ret;
+	}
+
+	int top() {
+		return q.front();
+	}
+
+	bool empty() {
+		return q.empty();
+	}
+};
+
+int main() {
+	MyStack s;
+	s.push(1);
+	s.push(2);
+	s.push(3);
+	std::cout << s.top() << "\n";
+	s.push(4);
+	s.push(5);
+	while (!s.empty()) {
+		std::cout << s.pop() << std::endl;
+	}
+}

cpp/2205/CMakeLists.txt

@@ -3,4 +3,4 @@ PROJECT(2205)
 
 SET(CMAKE_CXX_STANDARD 23)
 
-ADD_EXECUTABLE(2204 220505-CN.cpp)
+ADD_EXECUTABLE(2204 220505.cpp)