Suppose you are given an implementation of a queue of integers. The operations that can be performed on the queue are:
i. isEmpty (Q) — returns true if the queue is empty, false otherwise.
ii. delete (Q) — deletes the element at the front of the queue and returns its value.
iii. insert (Q, i) — inserts the integer i at the rear of the queue.
Consider the following function:

void f (queue Q) { 
  int i ; 
  if (!isEmpty(Q)) { 
      i = delete(Q); 
      f(Q); 
      insert(Q, i); 
  } 
} 

What operation is performed by the above function f ?

An implementation of a queue Q, using two stacks S1 and S2, is given below :

void insert(Q, X){
  push(S1, X);
}

void delete(Q){
if(stack - empty(S2)) then {
  if(stack - empty(S1)) then {
   print("Q is empty");
   return;
  }else while (!(stack - empty(S1))){
   X = pop(S1);
   push(S2, X);
 }
 X = pop(S2);
}

Let n insert and $$m( \le n)$$ delete operations be performed in an arbitrary order on an empty queue Q. Let x and y be the number of push and pop operations performed respectively in the process. Which one of the following is true for all m and n?

The following function computes the value of ^mC_n correctly for all legal values m and n (m≥1,n≥0 and m>n)

int func(int m, int n) 
{ 
     if (E) return 1; 
     else return(func(m -1, n) + func(m - 1, n - 1)); 
} 

In the above function, which of the following is the correct expression for E?

Assume that the operators +, -, ×, are left associative and ^ is right associative. The order of precedence (from highest to lowest) is ^, ×, +, -. The postfix expression corresponding to the infix expression a + b×c-d^e^f is