数据结构/PTA-在一个数组中实现两个堆栈/函数
本题要求在一个数组中实现两个堆栈。
函数接口定义:
Stack CreateStack( int MaxSize ); bool Push( Stack S, ElementType X, int Tag ); ElementType Pop( Stack S, int Tag );
其中Tag
是堆栈编号,取1或2;MaxSize
堆栈数组的规模;Stack
结构定义如下:
typedef int Position; struct SNode { ElementType *Data; Position Top1, Top2; int MaxSize; }; typedef struct SNode *Stack;
注意:如果堆栈已满,Push
函数必须输出“Stack Full”并且返回false;如果某堆栈是空的,则Pop
函数必须输出“Stack Tag Empty”(其中Tag是该堆栈的编号),并且返回ERROR。
裁判测试程序样例:
#include <stdio.h> #include <stdlib.h> #define ERROR 1e8 typedef int ElementType; typedef enum { push, pop, end } Operation; typedef enum { false, true } bool; typedef int Position; struct SNode { ElementType *Data; Position Top1, Top2; int MaxSize; }; typedef struct SNode *Stack; Stack CreateStack( int MaxSize ); bool Push( Stack S, ElementType X, int Tag ); ElementType Pop( Stack S, int Tag ); Operation GetOp(); /* details omitted */ void PrintStack( Stack S, int Tag ); /* details omitted */ int main() { int N, Tag, X; Stack S; int done = 0; scanf("%d", &N); S = CreateStack(N); while ( !done ) { switch( GetOp() ) { case push: scanf("%d %d", &Tag, &X); if (!Push(S, X, Tag)) printf("Stack %d is Full!\n", Tag); break; case pop: scanf("%d", &Tag); X = Pop(S, Tag); if ( X==ERROR ) printf("Stack %d is Empty!\n", Tag); break; case end: PrintStack(S, 1); PrintStack(S, 2); done = 1; break; } } return 0; } /* 你的代码将被嵌在这里 */
输入样例:
5 Push 1 1 Pop 2 Push 2 11 Push 1 2 Push 2 12 Pop 1 Push 2 13 Push 2 14 Push 1 3 Pop 2 End
输出样例:
Stack 2 Empty Stack 2 is Empty! Stack Full Stack 1 is Full! Pop from Stack 1: 1 Pop from Stack 2: 13 12 11
分析:
题目要求三个函数,建栈、入栈、出栈.
“在一个数组中实现两个堆栈”是指可以双向出入。我们来分析样例:
定义大小为5的栈
Push 1 1 顶入1
Pop 2 尾出元素,失败,报错
Push 2 11 尾入11
Push 1 2 顶入2
Push 2 12 尾入12
Pop 1 顶出元素,出2
Push 2 13 尾入13
Push 2 14 尾入14
Push 1 3 顶入3,失败,报错
Pop 2 尾出元素,出14
Stack CreateStack( int MaxSize ) { struct SNode *S=NULL; S=(struct SNode *)malloc(sizeof(struct SNode)); S->Data=(int *)malloc(MaxSize*sizeof(int)); S->Top1=-1; S->Top2=MaxSize; S->MaxSize=MaxSize; return S; } bool Push( Stack S, ElementType X, int Tag ) { if(S->Top2-S->Top1==1) { printf("Stack Full\n"); return false; } else { if(Tag==1) S->Data[++(S->Top1)]=X; else if(Tag==2) S->Data[--(S->Top2)]=X; return true; } } ElementType Pop( Stack S, int Tag ) { if(Tag==1) { if(S->Top1==-1) { printf("Stack %d Empty\n",Tag); return ERROR; } else return S->Data[(S->Top1)--]; } else if(Tag==2) { if(S->Top2==S->MaxSize) { printf("Stack %d Empty\n",Tag); return ERROR; } else { return S->Data[(S->Top2)++]; } } }