本題要求在一個數組中實現兩個堆棧。
函數接口定義:
Stack CreateStack( int MaxSize );
bool Push( Stack S, ElementType X, int Tag );
ElementType Pop( Stack S, int Tag );
其中Tag是堆棧編號,取1或2;MaxSize堆棧數組的規模;
Stack結構定義如下:
typedef int Position;
struct SNode {
ElementType *Data;
Position Top1, Top2;
int MaxSize;
};
typedef struct SNode *Stack;
注意:如果堆棧已滿,Push函數必須輸出“Stack Full”並且返回false;如果某堆棧是空的,則Pop函數必須輸出“Stack Tag Empty”(其中Tag是該堆棧的編號),並且返回ERROR。
裁判測試程序樣例:
#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;
}
/* 你的代碼將被嵌在這裏 */
輸入樣例:
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
輸出樣例:
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
阿偉讀完題後一臉懵逼,一開始以爲兩頭都是棧頂,,,經大佬提點之後才知道兩頭應該都是棧底。課本上棧的數組描述也是用的索引爲0的位置是棧底emmm
那這樣就簡單多了,在CreateStack函數中,爲了之後好判斷,將Top1設爲-1,Top2設爲MaxSize,由於編譯器是C的,所以在動態申請空間的時候不能用new,要用到malloc函數,具體動態申請數組空間的代碼爲:
s->Data=(int *)malloc(MaxSize*sizeof(int));//MaxSize爲數組大小
在push函數中,重要的就是數組是否滿了的判斷,如果Top1+1==Top2,則證明數組棧已經滿了
在pop函數中(這個函數最氣人),讀題發現我並不知道如果刪除成功後我要返回什麼。。之後翻看了大佬的代碼,才知道如果刪除成功要返回刪除的(之前的)棧頂元素(太氣人了,手動拍桌)
(還要感謝大佬補全了題目中沒給的兩個函數)
Operation GetOp()
{
char Push[] = "Push";
char Pop[] = "Pop";
char End[] = "End";
char s[100];
scanf("%s", s);
if (strcmp(Push, s) == 0)return push;
if (strcmp(Pop, s) == 0)return pop;
if (strcmp(End, s) == 0)return end;
}
void PrintStack(Stack S, int Tag)
{
printf("Pop from Stack %d:", Tag);
if (Tag == 1){
while (S->Top1 != -1){
printf(" %d", S->Data[S->Top1--]);
}
}
else {
while (S->Top2 != S->MaxSize){
printf(" %d", S->Data[S->Top2++]);
}
}
putchar('\n');
}
阿偉的AC代碼:
Stack CreateStack( int MaxSize )
{
Stack s=(Stack)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->Top1+1==S->Top2)
{
printf("Stack Full\n");
return false;
}
if(Tag==1)
{
S->Data[++S->Top1]=X;
}
else
S->Data[--S->Top2]=X;
return true;
}
ElementType Pop( Stack S, int Tag )
{
if((Tag==1&&S->Top1==-1)||(Tag==2&&S->Top2==S->MaxSize))
{
printf("Stack %d Empty\n",Tag);
return ERROR;
}
if(Tag==1)
return S->Data[S->Top1--];//返回新的棧頂元素
else
return S->Data[S->Top2++];
return 1;
}