1.栈的初始化等
代码

#include<iostream>

using namespace std;

#define MaxSize 50
typedef int ElemType;


typedef struct{
    ElemType data[MaxSize];
    int top;

}SqStack;

//1.初始化栈
void init(SqStack &S)
{
    S.top=-1;   
} 

//2.判断栈空
int isEmpty(SqStack S)
{
    if(S.top==-1)return 1;
    return 0;   
} 

//3.进栈
bool push(SqStack &S,ElemType x)
{
    if(S.top==MaxSize-1)return false;
    S.data[++S.top]=x;
    return true;    
} 

//4.出栈
bool pop(SqStack &S,ElemType&x)
{
    if(isEmpty(S))return false;

    x=S.data[S.top--];
    return true;
}

//5.读栈顶元素
bool top(SqStack S,ElemType&x)
{
    if(isEmpty(S))return false;

    x=S.data[S.top];
    return true;

} 

int main()
{
    SqStack stack;
    init(stack);

    int x;
    cout<<"输入一个十进制数"<<endl;
    cin>>x;

    while(x!=0)
    {
        push(stack,x%8);    
        x=x/8;
    } 
    while(!isEmpty(stack))
    {
        pop(stack,x);
        cout<<x;
    }

    return 0;   
} 


//判断IO(进栈出栈)序列是否合法
bool isRightful(char *str)
{
    int count=0;
    for(int i=0;str[i]!='\0';i++)
    {
        if(str[i]=='I')
        {
            count++;        
        }       
        else if(str[i]=='O')
        {
            if(count==0)
            {
                return false;
            }
            else
            {
                count--;
            }
        }
        else
        {
            return false;
        }
    }   
    return count==0;
}

2.加一个最小值栈
代码

typedef int ElemType

#define MaxSize=100

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

typedef struct{
    SqStack eStack;
    SqStack minStack;
}MEStack;

void init(MEStack &s)
{
    s.eStack.top=-1;
    s.minStack.top=-1;
}

bool top(MEStack s,ElemType &x1,ElemType &x2)
{
    if(s.eStack.top==-1||s.minStack.top==-1)
    {
        return false;
    }
    x1=s.eStack.data[s.eStack.top];
    x2=s.minStack.data[s.minStack.top];
    return true;
}

bool push(MEStack s,ElemType e)
{
    if(s.eStack.top==MaxSize-1||s.minStack.top==MaxSize-1)
    {
        return false;
    }
    s.eStack.data[++s.eStack.top]=e;
    ElemType x1,x2;
    top(s,x1,x2);
    s.minStack.data[++s.minStack.top]=min(e,x2);
    return true;
}

bool pop(MEStack s,ElemType &x1,ElemType &x2)
{
    if(s.eStack.top==-1||s.minStack.top==-1)
    {
        return false;
    }
    x1=s.eStack.data[s.eStack.top--];
    x2=s.minStack.data[s.minStack.top--];
    return true;
}

bool getMin(MEStack &s,ElemType &min)
{
    if(s.minStack.top==-1)
    {
        return false;
    }
    min=s.minStack.data[s.minStack.top];
}

3.设有两个栈S1,S2都采用顺序栈,并共享一个存储区[0..MaxSize-1],设计共享栈
思想：
1.栈空:S1初始为空,top1=-1,S2初始为空,top2==MaxSize
2.栈满:top1与top2相邻
S1入栈:栈不满的情况下,先top1++,再存储元素
S2入栈:栈满的情况下,先top2–,再存储元素

#define MaxSize 5
typedef int ElemType;

typedef struct{
    ElemType stack[MaxSize];
    int top[2];
}ShareStack; 

void initShareStack(ShareStack &S)
{
    S.top[0]=-1;
    S.top[1]=MaxSize;
}

bool push(ShareStack &S,int i,ElemType e)
{
    if(i<0||i>1)
    {
        return false;
    }
    //栈满 
    if(S.top[0]+1==S.top[1])
    {
        return false;
    }
    if(i==0)
    {
        S.stack[++S.top[0]]=e;  
    } 
    else if(i==1)
    {
        S.stack[--S.top[1]]=e;
    }
    return true;
}

bool pop(ShareStack &S,int i,ElemType&x)
{
    if(i<0||i>1)return false;
    //栈空
    if(i==0&&S.top[0]==-1)return false;
    if(i==1&&S.top[1]==MaxSize) return false;
    if(i==0)
    {
        x=S.data[S.top[0]--];
    }
    else if(i==1)
    {
        x=S.data[S.top[1]++];
    }
    return true;
}