双栈

双栈意思就是双向栈,基本思想就是在一段内存里面,栈从两边分别向中间生长,这样可以提高内存的利用率。下面是C的实现代码,仅仅是基本的功能,重在于思想。
[code]
#include <stdio.h>
#include <stdlib.h>

#define INIT_STACK_SIZE 100

typedef int ElemType;
typedef struct DoubleStack{
ElemType *array;
int top1; //SP for stack1
int top2; //SP for stack2
}DouStack,*pDouStack;

void InitialDouStack(pDouStack S);
void Push(pDouStack S,ElemType add_data,int flags);//flags==1,for stack1;flags==2,for stack2
void Pop(pDouStack S,ElemType *del_data,int flags);//flags==1,for stack1;flags==2,for stack2
void PrintDoubleStack(pDouStack S);

int main()
{
DouStack S;
InitialDouStack(&S);
for(int i = 1; i <= 20; ++i)
{
Push(&S,i,i%2 + 1);//for debug,flag2 is 1 or 2
}
PrintDoubleStack(&S); //print stack1 and stack2
ElemType temp = 0; //accept data pop from stack;
for(int i = 1; i <= 25; ++i)
{
Pop(&S,&temp,i%2 + 1);
}
PrintDoubleStack(&S);

return 0;
}

void InitialDouStack(pDouStack S)
{
S->array = (ElemType *)calloc(INIT_STACK_SIZE,sizeof(DouStack));
if(!S->array)
{
printf("allocate memory error \n");
return ;
}
S->top1 = 0;
S->top2 = INIT_STACK_SIZE;
}

void Push(pDouStack S,ElemType add_data,int flags)
{
if(S->top2 == S->top1)
{
printf("Full double stack\n");
return ;
}
switch(flags)
{
case 1: //push into stack1
S->array[S->top1++] = add_data;
break;
case 2: //push into stack2
S->array[--S->top2] = add_data;
break;
default :
return;
}
return;
}

void PrintDoubleStack(pDouStack S)
{
int top1 = S->top1;
int top2 = S->top2;

printf("Stack 1 : \n");
while(top1)
{
printf("Stack 1 %d : %d \n",top1,S->array[--top1]);
}

printf("Stack 2 : \n");
while(top2 < INIT_STACK_SIZE)
{
printf("Stack 2 %d : %d \n",top2,S->array[top2++]);
}
}

void Pop(pDouStack S,ElemType *del_data,int flags)
{
switch(flags)
{
case 1: //pop from stack1
if(S->top1 == 0)
{
printf("Stack1 is empty!\n");
return;
}
*del_data = S->array[--S->top1];
break;
case 2: //pop from stack2
if(S->top2 == INIT_STACK_SIZE)
{
printf("Stack2 is empty!\n");
return;
}
*del_data = S->array[S->top2++];
break;
}
}

[/code]

标签:DataStructure