# Most viewed questions in Programming and DS

1
The number of ways in which the numbers $1, 2, 3, 4, 5, 6, 7$ can be inserted in an empty binary search tree, such that the resulting tree has height $6$, is _________. Note: The height of a tree with a single node is $0$.
2
When searching for the key value $60$ in a binary search tree, nodes containing the key values $10, 20, 40, 50, 70, 80, 90$ are traversed, not necessarily in the order given. How many different orders are possible in which these key values can occur on the search path from the root to the node containing the value $60$? $35$ $64$ $128$ $5040$
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You are given the postorder traversal, $P$, of a binary search tree on the $n$ elements $1, 2, \dots, n$. You have to determine the unique binary search tree that has $P$ as its postorder traversal. What is the time complexity of the most efficient algorithm for doing this? $\Theta(\log n)$ $\Theta(n)$ $\Theta(n\log n)$ None of the above, as the tree cannot be uniquely determined
5
$N$ items are stored in a sorted doubly linked list. For a delete operation, a pointer is provided to the record to be deleted. For a decrease-key operation, a pointer is provided to the record on which the operation is to be performed. An algorithm performs the following operations on the list in this ... operations put together? $O(\log^{2} N)$ $O(N)$ $O(N^{2})$ $\Theta\left(N^{2}\log N\right)$
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Suppose we have a balanced binary search tree $T$ holding $n$ numbers. We are given two numbers $L$ and $H$ and wish to sum up all the numbers in $T$ that lie between $L$ and $H$. Suppose there are $m$ such numbers in $T$. If the tightest upper bound on the time to compute the sum is $O(n^a\log^bn+m^c\log^dn)$, the value of $a+10b+100c+1000d$ is ______.
7
In a min-heap with $n$ elements with the smallest element at the root, the $7^{th}$ smallest element can be found in time $\Theta (n \log n)$ $\Theta (n)$ $\Theta(\log n)$ $\Theta(1)$
8
Let $Q$ denote a queue containing sixteen numbers and $S$ be an empty stack. $Head(Q)$ returns the element at the head of the queue $Q$ without removing it from $Q$. Similarly $Top(S)$ returns the element at the top of $S$ without removing it from $S$. Consider ... ); else x:= Pop(S); Enqueue (Q, x); end end The maximum possible number of iterations of the while loop in the algorithm is _______.
9
What is the maximum height of any AVL-tree with $7$ nodes? Assume that the height of a tree with a single node is $0$. $2$ $3$ $4$ $5$
10
A program takes as input a balanced binary search tree with $n$ leaf nodes and computes the value of a function $g(x)$ for each node $x$. If the cost of computing $g(x)$ is: $\Large \min \left ( \substack{\text{number of leaf-nodes}\\\text{in left-subtree of$ ... the worst-case time complexity of the program is? $\Theta (n)$ $\Theta (n \log n)$ $\Theta(n^2)$ $\Theta (n^2\log n)$
11
Consider the following operation along with Enqueue and Dequeue operations on queues, where $k$ is a global parameter. MultiDequeue(Q){ m = k while (Q is not empty) and (m > 0) { Dequeue(Q) m = m – 1 } } What is the worst case time complexity of a sequence of $n$ queue operations on an initially empty queue? $Θ(n)$ $Θ(n + k)$ $Θ(nk)$ $Θ(n^2)$
12
Consider the following C program. #include<stdio.h> #include<string.h> int main() { char* c=”GATECSIT2017”; char* p=c; printf(“%d”, (int)strlen(c+2[p]-6[p]-1)); return 0; } The output of the program is _______
13
Consider the C code fragment given below. typedef struct node { int data; node* next; } node; void join(node* m, node* n) { node* p = n; while(p->next != NULL) { p = p->next; } p->next = m; } Assuming that m and n point to valid NULL-terminated linked ... or append list m to the end of list n. cause a null pointer dereference for all inputs. append list n to the end of list m for all inputs.
14
Consider the C functions foo and bar given below: int foo(int val) { int x=0; while(val > 0) { x = x + foo(val--); } return val; } int bar(int val) { int x = 0; while(val > 0) { x= x + bar(val-1); } ... $6$ and $6$ respectively. Infinite loop and abnormal termination respectively. Abnormal termination and infinite loop respectively. Both terminating abnormally.
15
A is an array $[2.....6, 2.....8, 2.......10]$ of elements. The starting location is $500$. The location of an element $A(5, 5, 5)$ using column major order is __________.
16
We are given a set of $n$ distinct elements and an unlabeled binary tree with $n$ nodes. In how many ways can we populate the tree with the given set so that it becomes a binary search tree? $0$ $1$ $n!$ $\frac{1} {n+1} .^{2n}C_n$
17
A circular queue has been implemented using a singly linked list where each node consists of a value and a single pointer pointing to the next node. We maintain exactly two external pointers FRONT and REAR pointing to the front node and the rear node of the queue, respectively. Which of the ... rear node points to the front node. (I) only. (II) only. Both (I) and (II). Neither (I) nor (II).
Consider the following C program. #include<stdio.h> #include<string.h> void printlength(char *s, char *t) { unsigned int c=0; int len = ((strlen(s) - strlen(t)) > c) ? strlen(s) : strlen(t); printf("%d\n", len); } void main() { char *x = "abc"; ... that $strlen$ is defined in $string.h$ as returning a value of type $size\_t$, which is an unsigned int. The output of the program is __________ .
What is the output of the following C code? Assume that the address of $x$ is $2000$ (in decimal) and an integer requires four bytes of memory. int main () { unsigned int x   = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}, {10, 11, 12}}; printf ("%u, %u, %u", x + 3, *(x + 3), *(x + 2) + 3); } $2036, 2036, 2036$ $2012, 4, 2204$ $2036, 10, 10$ $2012, 4, 6$
A binary search tree contains the value $1, 2, 3, 4, 5, 6, 7, 8$. The tree is traversed in pre-order and the values are printed out. Which of the following sequences is a valid output? $5 \ 3 \ 1 \ 2 \ 4 \ 7 \ 8 \ 6$ $5 \ 3 \ 1 \ 2 \ 6 \ 4 \ 8 \ 7$ $5 \ 3 \ 2 \ 4 \ 1 \ 6 \ 7 \ 8$ $5 \ 3 \ 1 \ 2 \ 4 \ 7 \ 6 \ 8$