MS - 2 - 设计包含 min 函数的栈

定义栈的数据结构，要求添加一个 min 函数，能够得到栈的最小元素。 要求函数 min、push 以及 pop 的时间复杂度都是 O(1)。

 template<typename T>
 struct MinStackElement
 {
     T data;
     T min;
 };

 template<typename T>
 struct MinStack
 {
     MinStack() : pData(NULL), size(), top(){}
     MinStackElement<T>* pData;
     int size;
     int top;
 };

 template<typename T>
 void MinStackInitialize(MinStack<T>& s, int maxSize)
 {
     MinStackFree(s);
      s.pData = (MinStackElement<T>*)malloc(maxSize*sizeof(MinStackElement<T>));
      memset(s.pData, , maxSize*sizeof(MinStackElement<T>));
      s.size = maxSize;
      s.top = ;
  }

  template<typename T>
  void MinStackFree(MinStack<T>& s)
  {
      if (s.pData)
      {
          free(s.pData);
          s.pData = nullptr;
      }

      s.size = ;
      s.top = ;
  }

  template<typename T>
  void MinStackPush(MinStack<T>& s, T data)
  {
      if (s.size == )
      {
          printf("Stack is not initialized.\n");
          return;
      }

      if (s.top == s.size)
      {
          printf("Stack is full.\n");
          return;
      }

      s.pData[s.top].data = data;
      s.pData[s.top].min = (s.top ==  ? data : s.pData[s.top - ].min);
      if (s.pData[s.top].min > data)
      {
          s.pData[s.top].min = data;
      }

      wcout << L"stack push " << data << endl;
      s.top++;
  }

  template<typename T>
  T MinStackPop(MinStack<T>& s)
  {
     if (s.top == )
     {
         printf("Stack is empty.\n");
         return -;
     }

     T data = s.pData[--s.top].data;
     wcout << L"stack pop " << data << endl;

     return data;
  }

 template<typename T>
 T MinStackGetMin(const MinStack<T>& s)
 {
     if (s.top == )
     {
         printf("Stack is empty.\n");
         return ;
     }

     T min = s.pData[s.top - ].min;
     printf("Min :%d\n", min);

     return min;
 }

 int _tmain(int argc, _TCHAR* argv[])
 {
     int min = ;
     MinStack<int> s;

     MinStackPush(s, );

     MinStackInitialize(s, );
     MinStackPush(s, );
     MinStackPush(s, );
     MinStackPush(s, );
     MinStackPush(s, );
     MinStackPop(s);
     MinStackGetMin(s);
     MinStackPush(s, );
     MinStackPush(s, );
     MinStackPush(s, );

     MinStackPop(s);

     MinStackPush(s, );
     MinStackPush(s, );

     MinStackGetMin(s);

     MinStackPop(s);
     MinStackGetMin(s);
     MinStackPop(s);
     MinStackGetMin(s);
     MinStackPop(s);
     MinStackGetMin(s);
     MinStackPop(s);
     MinStackGetMin(s);
     MinStackPop(s);
     MinStackGetMin(s);
     MinStackPop(s);
     MinStackPop(s);
     MinStackPop(s);
     MinStackGetMin(s);

     MinStackFree(s);

     return ;
 }

>test.exe
Stack is not initialized.
stack push 9
stack push 5
stack push 6
stack push 4
stack pop 4
Min :5
stack push 3
stack push 8
stack push 2
stack pop 2
stack push 7
stack push 1
Min :1
stack pop 1
Min :3
stack pop 7
Min :3
stack pop 8
Min :3
stack pop 3
Min :5
stack pop 6
Min :5
stack pop 5
stack pop 9
Stack is empty.
Stack is empty.