Stack example - train cars reorganization

A set of train car number 1-n

From right to left through the station

Each car can temporarily stop (stack), let the few cars on the main line and then back on the road to keep up.

Sequence number and the carriages enter the compartment wanted, it is determined whether it is possible.

The CCF materials volumes P149, Example 6.9

code show as below:

 1 #include <iostream>
 2 #include <string>
 3 #include <cmath>
 4 #include <algorithm>
 5 using namespace std;
 6 struct Stack
 7 {
 8     int a[100];
 9     int p;
10 };
11 bool isempty(Stack *s)
12 {
13     return s->p==-1;
14 }
15 void push(Stack *s,int x)
16 {
17     s->p++;
18     s->a[s->p]=x;
19 }
20 int pop(Stack *s)
21 {
22     if(!isempty(s))
23     {
24         return s->a[s->p--];
25     }
26     else
27     {
28         //cout<<"The stack is empty";
29         return -1;
30     }
31 }
32 int gettop(Stack *s)
33 {
34     if(!isempty(s))
35     {
36         return s->a[s->p];
37     }
38     else
39     {
40         //cout<<"The stack is empty";
41         return -1;
42     }
43 }
44 main()
45 {
46     Stack *mystack=new Stack;
47     int a[100]={0},b[100]={0},n,*p1,*p2;//A is a sequence of interest, b is the initial sequence, b train through the station from right to left 
48      BOOL In Flag = to true ;
 49      mystack-> P = - . 1 ;
 50      P1 = a;
 51 is      P2 = B;
 52 is      // initialization start 
53 is      CIN >> n-;
 54 is      for ( int I = 0 ; I <n-; I ++ )
 55      {
 56 is          B [I] = I + . 1 ;
 57 is      }
 58      for ( int I = 0 ; I <n-; I ++ )
 59      {
 60         >> CIN A [I];
 61 is      }
 62 is      // initialization end 
63 is      the while (! * P1 = 0 )
 64      {
 65          IF (P2 * == 0 ! && getTop (myStack) * = P1)
 66          {
 67              In Flag = to false ;
 68              BREAK ;
 69          }
 70          the else 
71 is          {
 72              IF (== * P1 * P2)
 73 is              {
 74                  P1 ++ ;
 75                  P2 ++;
76             }
77             else if(*p1==gettop(mystack))
78             {
79                 pop(mystack);
80                 p1++;
81             }
82             else
83             {
84                 push(mystack,*p2);
85                 p2++;
86             }
87         }
88     }
89     if(flag)
90     {
91         cout<<"I can do it.";
92     }
93     else
94     {
95         cout<<"That is impossible.";
96     }
97     free(mystack);
98 }

end here