常见算法题：判断表达式括号是否匹配

#include<iostream>
#include<string>
using namespace std;
#define MaxSize 20
//字符串栈
class Stack
{
char *data;
int top;
public:
Stack();
~Stack();
bool IsEmpty();
bool Push(char e);
bool Pop(char& e);
};

Stack::Stack()
{
data = new char[MaxSize];
top = -1;
}

Stack::~Stack()
{
delete [] data;
}

bool Stack::IsEmpty()
{
return (top == -1);
}

bool Stack::Push(char e)
{
if(top == MaxSize-1)    return false;   //栈满
top++;
data[top] = e;
return true;
}

bool Stack::Pop(char& e)
{
if(top == -1)   return false;   //栈空
e = data[top];
top--;
return true;
}

bool IsMatch(char str[],int n)
{
int i=0;
char e;
Stack st;   //建立顺序栈
while(i<n)
{
if(str[i] == '(' || str[i] == '[' || str[i] == '{')
st.Push(str[i]);
else
{
if(str[i] == ')')
{
if(!st.Pop(e))  return false;
if(e!='(')  return false;
}
if(str[i] == ']')
{
if(!st.Pop(e))  return false;
if(e!='[')  return false;
}
if(str[i] == '}')
{
if(!st.Pop(e))  return false;
if(e!='{')  return false;
}
}
i++;
}
if(st.IsEmpty())    return true;
else return false;  //遍历字符串后栈不为空说明有不匹配字符
}

void main()
{
cout<<"请输入表达式："<<endl;
char str[MaxSize];
cin>>str;
int n = strlen(str);
if(IsMatch(str,n))
cout<<"表达式"<<str<<"中的括号是匹配的"<<endl;
else
cout<<"表达式"<<str<<"中的括号是不匹配的"<<endl;
}