minStack实现

设计包含 min 函数的栈(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)。

#include <algorithm>
#include <iostream>
#include <exception>
#include <string>

class illegalParameterValue
{
    public:
        illegalParameterValue():errorMessage("Illegal parameter value"){}
        illegalParameterValue(const char* theMessage){ errorMessage = theMessage;}
        std::string errorMessage;
};

template<typename T>
struct minStackElement{
    T element;
    T min;
};

template<typename T>
class minStack{
private:
    int top;
    int size;
    minStackElement<T>* arrayStack;
public:
    minStack(int initCapacity)
    {
        try{
            if(initCapacity < 1)
                throw illegalParameterValue("initCapacity must greater than 0");
        }catch(illegalParameterValue& e){
            std::cout << "initCapacity has been made to be 1" << std::endl;
            initCapacity = 1;
        }
        arrayStack = new minStackElement<T>[initCapacity];
        size = initCapacity;
        top = -1;
    }
    ~minStack()
    {
        delete [] arrayStack;
    }
    void push(T x)
    {
        minStackElement<T> e;
        e.element = x;
        if(top == -1){
            e.min = x;
        }else if(x < arrayStack[top].min){
            e.min = x;
        }else{
            e.min = arrayStack[top].min;
        }
        if(top == size-1)
        {
            minStackElement<T>* temp = arrayStack;
            arrayStack = new minStackElement<T>[2*size];
            std::copy(temp,temp+size-1,arrayStack);
            delete [] temp;
        }
        arrayStack[++top] = e;
    }

    void pop()
    {
        if(top == -1)
            throw illegalParameterValue("the stack is empty");
        top--;
    }

    T min()
    {
        return arrayStack[top].min;
    }
};