数据结构与算法分析——栈

#ifndef _Stack_H

struct Node;
typedef struct Node *PtrToNode;
typedef PtrToNode Stack;
typedef int ElementType;

int IsEmpty(Stack S);
Stack CreateStack(void);
void Push(ElementType X, Stack S);
void Pop(Stack S);
ElementType Top(Stack S);

#endif

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include "Stack.h"

struct Node
{
ElementType Element;
PtrToNode Next;
};

void FatalError(const char *Str)
{
printf("%s\n",(*Str));
exit(-1);
}

int IsEmpty(Stack S)
{
return S->Next == NULL;
}

/* Create a empty Stack */
Stack CreateStack(void)
{
Stack S;

S = malloc(sizeof(struct Node));
if(S == NULL)
FatalError("Out of space!!!\n");
S->Next = NULL;

return S;
}

/* Push X into Stack S*/
void Push(ElementType X, Stack S)
{
PtrToNode TmpCell;

TmpCell = malloc(sizeof(struct Node));
if(TmpCell == NULL)
FatalError("Out of space!!!\n");
else
{
TmpCell->Element = X;
TmpCell->Next = S->Next;
S->Next = TmpCell;
}
}

ElementType Top(Stack S)
{
if(!IsEmpty(S))
return S->Next->Element;
printf("IsEmpty Stack");
return 0;
}

void Pop(Stack S)
{
PtrToNode FirstCell;

if(IsEmpty(S))
printf("Empty Stack\n");
else
{
FirstCell = S->Next;
S->Next = FirstCell->Next;
free(FirstCell);
}
}