Question

2. Stacks and Queues Reinernber: Consider the following function: void systery( int num) { int current: /* create Stack stk and Queue que / Stacks: the function push places the given parameter on the top of the stack, the function pop removes and returns the top of the stack, and the function empty returns true (i.c., 1) if the stack is empty or false (i.e., 0) otherwise. Queues: the function insert places the given parameter on the end of the queue, the function remove removes and returns the front element of the queue, and the function empty returns true (i.e., 1) iſ the queue is empty or false (ie., 0) otherwise. while( num > 0 ) { if(num > 8 ) insert (que, nun); else push(atk, num); num - num - 2: Suppose we call mystery (14). What does this print out? while( empty(atk) != 1 ){ current = pop(stk); insert(que, current); printf("%d ", current); printf("\n"); whileempty(que) -1 ){ current - remove(que); push(&tk, current): printf("%d ", current); printf("\n"); while( empty(atk) - 1 current = pop(stk); if( empty(atk) != 1 ) { insert (que, current); current = pop(atk); Suppose we replace que with a priority queue. In particular assume that the function remove removes and returns the largest element of the queue. What does a call to mystery(14) print out now? printf("%d", current); printf("\n"); while( empty (que) !- 1 ){ current - remove(que); printf("%d ", current); printf("\n");

Answer 1

Note

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Given mystery(14)

Inside mystery() function first while loop will be executed
   First while loop:
         when num=14
             Here 14>8
                 so 14 will be inserted to queue --> que(14)
             num=14-2=12
        when num=12
             Here 12>8
                 so 12 will be inserted to queue --> que(14,12)
             num becomes 10
        when num=10
             similar to above
             10 will be inserted to queue -->que(14,12,10)
         num becomes 8

        when num=8
            Here 8 is not greater than 8, so else loop will execute
            8 will be pushed to stack--> stk(8)
            num becomes 6

       similary for different values of num 6, 4,2, num will be pushed to stack
            so stack becomes--> stk(2,4,6,8)

  
    In second while loop:
         when stack is not empty:
             pop(stk) gets 2 and makes -->stk(4,6,8)
             insert 2 to que makes---> que(14,12,10,2)
             print(2)

             Similary 4,6,8 will be poped and inserted to que
   At the end stack--> stk()
                    queue--> que(14,12,10,2,4,6,8)
            print(4,6,8)
        print(newline)

    In third while loop:
        while queue is not empty
            remove each element from fornt of queue and push to stack
           At the end stack--> stk(8,6,4,2,10,12,14)
                    queue--> que()
            print(14,12,10,2,4,6,8)
            print(newline)

    In fourth while loop
        while stack is not empty
            pop an element from stack
            insert the element to queue only if stack is not empty after pop
            At the end stack-stk()
                  queue --> que(8,6,4,2,10,12)
            print(8,6,4,2,10,12,14)
            print(newline)

    In fifth while loop
         while queue is not empty
            remove an element from queue and print the element
          
            At the end stack-stk()
                  queue -->que()
            print(8,6,4,2,10,12)

So final result is
2 4 6 8
14 12 10 2 4 6 8
8 6 4 2 10 12 14
8 6 4 2 10 12
//############################################################################################

When que is priority queue
***************************
Given mystery(14)

Inside mystery() function first while loop will be executed
   First while loop:
         when num=14
             Here 14>8
                 so 14 will be inserted to queue --> que(14)
             num=14-2=12
        when num=12
             Here 12>8
                 so 12 will be inserted to queue --> que(14,12)
             num becomes 10
        when num=10
             similar to above
             10 will be inserted to queue -->que(14,12,10)
         num becomes 8

        when num=8
            Here 8 is not greater than 8, so else loop will execute
            8 will be pushed to stack--> stk(8)
            num becomes 6

       similary for different values of num 6, 4,2, num will be pushed to stack
            so stack becomes--> stk(2,4,6,8)

  
    In second while loop:
         when stack is not empty:
             pop(stk) gets 2 and makes -->stk(4,6,8)
             insert 2 to que makes---> que(14,12,10,2)
             print(2)

             Similary 4,6,8 will be poped and inserted to que
   At the end stack--> stk()
                    queue--> que(14,12,10,2,4,6,8)
            print(4,6,8)
        print(newline)

    In third while loop:
        while queue is not empty
           remove largest element from queue and push it to stack
          At the end queue will become-->que()
                                 stack--> stk(2,4,6,8,12,14)
          print(14,12,10,8,6,4,2)
          print(newline)

   In fourth while loop
        while stack is not empty
            pop an element from stack
            insert the element to queue only if stack is not empty after pop
            At the end stack-stk()
                  queue --> que(2,4,6,8,10,12)
            print(2,4,6,8,10,12,14)
            print(newline)

   In fifth while loop
         while queue is not empty
            remove an element from queue and print the element
          
            At the end stack-stk()
                  queue -->que()
            print(2,4,6,8,10,12)

So final result is
2 4 6 8
14 12 10 8 6 4 2
2 4 6 8 10 12 14
2 4 6 8 10 12