共享棧

共享棧，便是兩個棧使用同一段存儲空間。

第一個棧從數組頭開始存儲，第二個棧從數組尾開始，兩個棧向中間拓展。

當top1+1==top2或者top1==top2-1時，即staock overflow!.

與普通棧同樣，共享棧出棧入棧的時間複雜度仍爲O(1).

數據結構

typedef struct shareStack{ int data[MAXSIZE]; int top1; int top2; }shareStack;

出棧操做

該數據，僅存的是非負數，所以若是想要存儲更復雜的操做，能夠在判斷棧空時，換一種方式，便可。

int Pop(shareStack *ss,int flag){ if(flag == 1){ if(ss->top1 == -1) return -1; return ss->data[ss->top1--]; }else if(flag == 2){ if(ss->top2 == MAXSIZE) return -1; return ss->data[ss->top2++]; } return -1; }

入棧操做

int Push(shareStack *ss,int num,int flag){ if(ss->top1+1 == ss->top2) return 0; if(flag == 1){ ss->data[++ss->top1] = num; return 1; }else if( flag == 2){ ss->data[--ss->top2] = num; return 1; } return 0; }

示例代碼

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #define MAXSIZE 20
 4 
 5 typedef struct shareStack{  6     int data[MAXSIZE];  7     int top1;  8     int top2;  9 }shareStack;  10 
 11 void createStack(shareStack * ss,int n,int m);  12 void showStack(shareStack *ss);  13 int Push(shareStack *ss,int num,int flag);  14 int Pop(shareStack *ss,int flag);  15 
 16 int main()  17 {  18     shareStack * ss = (shareStack *)malloc(sizeof(shareStack));  19 
 20     createStack(ss,3,4);  21  showStack(ss);  22 
 23     if(Push(ss,6,1))  24  showStack(ss);  25 
 26     if(Push(ss,4,2))  27  showStack(ss);  28 
 29     int n;  30     n=Pop(ss,1);  31     if(n>=0)  32         printf("the pop num is:%d\n",n);  33     n=Pop(ss,2);  34     if(n>=0)  35         printf("the pop num is:%d\n",n);  36     n=Pop(ss,1);  37     if(n>=0)  38         printf("the pop num is:%d\n",n);  39     n=Pop(ss,1);  40     if(n>=0)  41         printf("the pop num is:%d\n",n);  42     n=Pop(ss,1);  43     if(n>=0)  44         printf("the pop num is:%d\n",n);  45     n=Pop(ss,1);  46     if(n>=0)  47         printf("the pop num is:%d\n",n);  48     n=Pop(ss,1);  49     if(n>=0)  50         printf("the pop num is:%d\n",n);  51 
 52  showStack(ss);  53 
 54     return 0;  55 }  56 
 57 void createStack(shareStack * ss,int n,int m){  58     int i;  59     ss->top1 = -1;  60     ss->top2 = MAXSIZE;  61     for(i=0;i<n;i++){  62         ss->top1++;  63         ss->data[ss->top1] = 2*i+1;  64  }  65     for(i=0;i<m;i++){  66         ss->top2--;  67         ss->data[ss->top2] = 2*i+1;  68  }  69 }  70 
 71 void showStack(shareStack *ss){  72     int i;  73     for(i=0;i<ss->top1+1;i++){  74         printf("%d->",ss->data[i]);  75  }  76     printf("top1-----top2");  77     for(i=ss->top2;i<MAXSIZE;i++){  78         printf("<-%d",ss->data[i]);  79  }  80     printf("\n");  81 }  82 
 83 int Push(shareStack *ss,int num,int flag){  84     if(ss->top1+1 == ss->top2)  85         return 0;  86     if(flag == 1){  87         ss->data[++ss->top1] = num;  88         return 1;  89     }else if( flag == 2){  90         ss->data[--ss->top2] = num;  91         return 1;  92  }  93     return 0;  94 }  95 
 96 int Pop(shareStack *ss,int flag){  97     if(flag == 1){  98         if(ss->top1 == -1)  99             return -1; 100         return ss->data[ss->top1--]; 101     }else if(flag == 2){ 102         if(ss->top2 == MAXSIZE) 103             return -1; 104         return ss->data[ss->top2++]; 105  } 106     return -1; 107 }

運行結果