1
GATE CSE 2006
+2
-0.6
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(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?
A
$$n + m \le x \le 2n$$ and $$2m \le y \le n + m$$
B
$$n + m \le x \le 2n$$ and $$2m \le y \le 2n$$
C
$$2m \le x \le 2n$$ and $$2m \le y \le n + m$$
D
$$2m \le x \le 2n$$ and $$2m \le y \le 2n$$
2
GATE CSE 2006
+2
-0.6
The following function computes the value of mCn 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?
A
(n = = 0) || (m = = 1)
B
(n = = 0) && (m = = 1)
C
(n = = 0) || (m = = n)
D
(n = = 0) && (m = = n)
3
GATE CSE 2004
+2
-0.6
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
A
abc×+def^^-
B
abc×+de^f^-
C
ab+c×d-e^f^
D
- + a×bc^^def
4
GATE CSE 2004
+2
-0.6
A program attempts to generate as many permutation as possible of the string “abcd” by pushing the character a,b,c,d in the same order onto a stack, but it may pop off the top character at any time. Which one of the following a strings CANNOT be generated using this program?
A
abcd
B
dcba
C
D
cabd
GATE CSE Subjects
Discrete Mathematics
Programming Languages
Theory of Computation
Operating Systems
Digital Logic
Computer Organization
Database Management System
Data Structures
Computer Networks
Algorithms
Compiler Design
Software Engineering
Web Technologies
General Aptitude
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