练习六——链式栈+括号匹配

#include <iostream>
#include <assert.h>
#include <cstring>

using namespace std;
struct StackNode{
public:
    char data;
    struct StackNode *link;
    StackNode(char d='@',StackNode *next=NULL):data(d),link(next){}
};
class LinkedStack{
private:
    StackNode *top;
public:
    LinkedStack():top(NULL){}
    ~LinkedStack(){makeEmpty();}
    void makeEmpty();
    void Push(char &x);
    char Pop(char &x);
    char getTop(char &x) const;
    char IsEmpty() const {return (top==NULL)? 1:0;}
    char getSize()const;
    void output();
};
void LinkedStack::makeEmpty(){
    StackNode *p;
    while(top!=NULL){
        p=top;
        top=top->link;
        delete p;
    }
}
void LinkedStack::Push(char &x){
    top=new StackNode(x,top);
    assert(top!=NULL);
}
char LinkedStack::Pop(char &x){
    if(IsEmpty()){
        return 0;
    }
    StackNode *p=top;
    top=top->link;
    x=p->data;
    delete p;
    return 1;
}
char LinkedStack::getTop(char &x)const{
    if(IsEmpty()){
        return 0;
    }
    x=top->data;
    return 1;
}
void LinkedStack::output(){
    StackNode *p=top;
    while(p!=NULL){
        cout<<p->data<<endl;
        p=p->link;
    }
}
int Matching(char *exp){
    int state=1;int i=0;
    int l=strlen(exp);
    char x;
    LinkedStack s;
    while(i<l){
        char t=exp[i];
        switch(t){
            case '(':
                s.Push(t);
                break;
            case '[':
                s.Push(t);break;
            case '{':
                s.Push(t);break;
            case ')':
                if(s.Pop(x)&&x=='(') {
                    break;
                }
                else {
                    s.Pop(x);
                    cout<<x<<endl;
                    return 0;
                }
            case ']':
                if(s.Pop(x)&&x==']')
                    break;
                else
                    return 0;
            case '}':
                if(s.Pop(x)&&x=='{')
                    break;
                else
                    return 0;
        }
        i++;
    }
    if(s.IsEmpty())
        return 1;
    else
        return 0;
}
int main(){
    cout<<"begin"<<endl;
    char exp[3];
    for(int i=0;i<3;i++){
        cin>>exp[i];
    }
    cout<<Matching(exp);
    return 0;
}