数据结构之栈

顺序栈

定义

#define MaxSize 10
typedef struct
{
    ElemType data[MaxSize];
    int top;
}SqStack;

初始化

void InitStack(SqStack &S)
{
    S.top=-1;
}

判空

bool StackEmpty(SqStack &S)
{
    if(S.top==-1)
        return true;
    return false;
}

入栈

bool Push(SqStack &S,ElemType x)
{
    if(S.top == MaxSize-1)
        return false;
    S.data[++S.top]=x;
    return true;
}

出栈

bool Pop(SqStack &S,ElemType &x)
{
    if(S.top==-1)
        return false;
    x = S.data[S.top]
    S.top--;
    return true;
}

获取栈顶元素

bool GetTop(SqStack &S,ElemType &x)
{
    if(S.top == -1)
        return false;
    x = S.data[S.top];
    return true;
}

链栈

定义

typedef struct LinkNode
{
    ElemType data;
    struct LinkNode *next;
}*LStack;

初始化

bool InitLStack(LStack &L)
{
    L = (StackNode*)malloc(sizeof(StackNode));
    if(L == NULL)
        return false;
    L->next = NULL;
    return true;
}

判空

bool LStackEmpty(LStack L)
{
    if(L->next == NULL)
        return true;
    return false;
}

入栈

bool Push(LStack &L,ElemType e)
{
    StackNode *node = (StackNode*)malloc(sizeof(StackNode));
    if(node == NULL)
        return false;
    node->data = e;
    node->next = L->next;
    L->next = node;
    return true;
}

出栈

bool Pop(LStack &L,ElemType &e)
{
    if(L->next == NULL)
        return false;
    StackNode *node  = L->next;
    e = node->data;
    L->next = node->next;
    free(node);
    return true;
}

获取栈顶元素

bool getTop(LStack &L,ElemType &e)
{
    if(L->next == NULL)
        return false;
    e = L->next->data;
    return true;
}

经典题练习

sdut括号匹配

括号匹配

#include<bits/stdc++.h>
using namespace std;
const int MaxSize = 50+5;
typedef struct
{
    char data[MaxSize];
    int top;
} sqStack;

void InitStack(sqStack &S)
{
    S.top=-1;
}

bool StackEmpty(sqStack &S)
{
    return S.top==-1;
}

bool Push(sqStack &S,char x)
{
    if(S.top==MaxSize-1)
        return false;
    S.data[++S.top] = x;
    return true;
}

bool Pop(sqStack &S,char &x)
{
    if(StackEmpty(S))
        return false;
    x = S.data[S.top];
    S.top--;
    return true;
}
int main()
{
    bool legal;
    sqStack S;
    string str;
    while(getline(cin,str))
    {
        legal = true;
        InitStack(S);//初始化栈
        for(int i = 0; i < str.length(); i++)
        {
            if(str[i] == '(' || str[i] == '[' || str[i]=='{')
            {
                Push(S,str[i]);
            }
            else if(str[i] == ')' || str[i] == ']' || str[i] == '}')
            {
                if(StackEmpty(S))
                {
                    legal = false;
                    break;
                }
                char topElem;
                Pop(S,topElem);
                if(topElem == '(' && str[i] !=')')
                    legal = false;
                if(topElem == '[' && str[i] !=']')
                    legal = false;
                if(topElem == '{' && str[i] !='}')
                    legal = false;
                if(legal == false)
                    break;
            }
        }
        if(legal == true && StackEmpty(S))
            cout<<"yes"<<endl;
        else 
            cout<<"no"<<endl;
    }
    return 0;
}