Add Datastructure: Stack

Author: icgw

DataStructure/Stack/example.cpp

@@ -0,0 +1,29 @@
+/*
+ * example.cpp
+ * Copyright (C) 2019 Guowei Chen <[email protected]>
+ *
+ * Distributed under terms of the MIT license.
+ */
+
+
+#include <iostream>
+#include "stack.hpp"
+
+int main()
+{
+  stack stk;
+  stk.push(1);
+  stk.push(2);
+
+  std::cout << "After push 1, 2, then stk.top() => " << stk.top() << "\n";
+
+  stk.pop();
+  std::cout << "After push 1, 2, pop, then stk.top() => " << stk.top() << "\n";
+  stk.pop();
+
+  stk.push(3);
+  std::cout << "After push 1, 2, pop, pop, push 3, then stk.top() => ";
+  std::cout << stk.top() << "\n";
+
+  return 0;
+}

DataStructure/Stack/stack.hpp

@@ -0,0 +1,85 @@
+/*
+ * stack.hpp
+ * Copyright (C) 2019 Guowei Chen <[email protected]>
+ *
+ * Distributed under terms of the MIT license.
+ */
+
+#ifndef _STACK_HPP_
+#define _STACK_HPP_
+
+#include <cstdlib>
+
+static constexpr int M = 10;
+
+class stack {
+public:
+  stack();
+  stack(int size);
+  ~stack();
+
+  void push(int n);
+  int  pop();
+  int  top();
+
+private:
+  int * _arr    = nullptr;
+  int _top      = -1;
+  int _capacity = 0;
+
+  bool isFull();
+  bool isEmpty();
+};
+
+bool stack::isFull() {
+  return _top >= _capacity - 1;
+}
+
+bool stack::isEmpty() {
+  return _top <= -1;
+}
+
+stack::stack() {
+  _arr      = (int *) malloc(M * sizeof(int));
+  _top      = -1;
+  _capacity = M;
+}
+
+stack::stack(int size) {
+  _arr      = (int *) malloc(size * sizeof(int));
+  _top      = -1;
+  _capacity = size;
+}
+
+stack::~stack() {
+  if (_arr != nullptr) {
+    free(_arr);
+    _arr = nullptr;
+  }
+}
+
+inline
+void stack::push(int n) {
+  if (isFull()) {
+    // TODO: throw an exception.
+  }
+  _arr[++_top] = n;
+}
+
+inline
+int stack::pop() {
+  if (isEmpty()) {
+    // TODO: throw an exception.
+  }
+  return _arr[_top--];
+}
+
+inline
+int stack::top() {
+  if (isEmpty()) {
+    // TODO: throw an exception.
+  }
+  return _arr[_top];
+}
+
+#endif // ifndef _STACK_HPP_