# Recent questions tagged cmi2015

1
A binary relation $R ⊆ (S S)$ is said to be Euclidean if for every $a, b, c ∈ S, (a, b) ∈ R$ and $(a, c) ∈ R$ implies $(b, c) ∈ R$. Which of the following statements is valid? If $R$ is Euclidean, $(b, a) ∈ R$ and $(c, a) ∈ R$, then $(b, c) ∈ R$, for every $a, b, c ∈ S$ ... $R$ is Euclidean, $(a, b) ∈ R$ and $(b, c) ∈ R$, then $(a, c) ∈ R$, for every $a, b, c ∈ S$ None of the above.
2
A college prepares its timetable by grouping courses in slots A, B, C, . . . All courses in a slot meet at the same time, and courses in different slots have disjoint timings. Course registration has been completed and the administration now knows which ... courses with an overlapping audience. In this setting, the graph theoretic question to be answered is: Find a maximum size independent set.
3
A college prepares its timetable by grouping courses in slots A, B, C, . . . All courses in a slot meet at the same time, and courses in different slots have disjoint timings. Course registration has been completed and the administration now knows which ... spanning tree with minimum number of edges. Find a minimal colouring. Find a minimum size vertex cover. Find a maximum size independent set
4
A college prepares its timetable by grouping courses in slots A, B, C, . . . All courses in a slot meet at the same time, and courses in different slots have disjoint timings. Course registration has been completed and the administration now knows which ... pairs of courses with an overlapping audience. In this setting, the graph theoretic question to be answered is: Find a minimal colouring.
5
There is a thin, long and hollow fibre with a virus in the centre. The virus occasionally becomes active and secretes some side products. The fibre is so thin that new side products secreted by the virus push the old products along the ... if a single virus could possibly have produced the given sequence. Use dynamic programming, checking smaller subsequences before checking bigger subsequences.
6
Consider the code below, defining the functions $f$ and $g$: f(m, n) { if (m == 0) return n; else { q = m div 10; r = m mod 10; return f(q, 10*n + r); } } g(m, n) { if (n == 0) return m; else { q = m div 10; r = m mod 10; return g(f(f(q, 0), r), n-1); } } How much time does it take to compute $f(m, n)$ and $g(m, n)$?
7
Consider the code below, defining the functions $f$ and $g$: f(m, n) { if (m == 0) return n; else { q = m div 10; r = m mod 10; return f(q, 10*n + r); } } g(m, n) { if (n == 0) return m; else { q = m div 10; r = m mod 10; return g(f(f(q, 0), r), n-1); } } What does $g(m, n)$ compute, for nonnegative numbers $m$ and $n$?
8
Consider the code below, defining the functions $f$ and $g$: f(m, n) { if (m == 0) return n; else { q = m div 10; r = m mod 10; return f(q, 10*n + r); } } g(m, n) { if (n == 0) return m; else { q = m div 10; r = m mod 10; return g(f(f(q, 0), r), n-1); } } Compute $g(3, 7), \: g(345, 1), \: g(345, 4) \text{ and } \: g(345, 0)$.
9
An airline runs flights between several cities of the world. Every flight connects two cities. A millionaire wants to travel from Chennai to Timbuktu by changing at most $k_1$ flights. Being a millionaire with plenty of time and money, he does not mind revisiting the ... change flights at most $k_1$ times. You can assume that the procedure can add or multiply two numbers in a single operation.
10
You are given $n$ positive integers, $d_1, d_2 \dots d_n$, each greater than $0$. Design a greedy algorithm to test whether these integers correspond to the degrees of some $n$-vertex simple undirected graph $G = (V, E)$. [A simple graph has no self-loops and at most one edge between any pair of vertices].
11
A cook has a kitchen at the top of a hill, where she can prepare rotis. Each roti costs one rupee to prepare. She can sell rotis for two rupees a piece at a stall down the hill. Once she goes down the steep hill, she can not climb back in time make more rotis. Suppose ... If she starts at the top with $P$ paans and $1$ rupee, what is the minimum and maximum amount of money she can have at the end?
12
A cook has a kitchen at the top of a hill, where she can prepare rotis. Each roti costs one rupee to prepare. She can sell rotis for two rupees a piece at a stall down the hill. Once she goes down the steep hill, she can not climb back in time make more rotis. Suppose the cook starts at the top with $R$ rupees. What are all the possible amounts of money she can have at the end?
13
Consider a social network with $n$ persons. Two persons $A$ and $B$ are said to be connected if either they are friends or they are related through a sequence of friends: that is, there exists a set of persons $F_1, \dots, F_m$ such that $A$ and $F_1$ ... friends. It is known that there are $k$ persons such that no pair among them is connected. What is the maximum number of friendships possible?
14
The school athletics coach has to choose $4$ students for the relay team. He calculates that there are $3876$ ways of choosing the team if the order in which the runners are placed is not considered. How many ways are there of choosing the team if the order of the runners is to be ... Between $12,000$ and $25,000$ Between $75,000$ and $99,999$ Between $30,000$ and $60,000$ More than $100,000$
15
Let $L_1$ and $L_2$ be languages over an alphabet $\Sigma$ such that $L_1 \subseteq L_2$. Which of the following is true: If $L_2$ is regular, then $L_1$ must also be regular. If $L_1$ is regular, then $L_2$ must also be regular. Either both $L_1$ and $L_2$ are regular, or both are not regular. None of the above.
16
How many times is the comparison $i \geq n$ performed in the following program? int i=85, n=5; main() { while (i >= n) { i=i-1; n=n+1; } } $40$ $41$ $42$ $43$
17
You arrive at a snack bar and you can't decide whether to order a lime juice or a lassi. You decide to throw a fair $6$-sided die to make the choice, as follows. If you throw $2$ or $6$ you order a lime juice. If you throw a $4$, you order a lassi. Otherwise, you throw the die ... is the probability that you end up ordering a lime juice? $\frac{1}{3}$ $\frac{1}{2}$ $\frac{2}{3}$ $\frac{3}{4}$
18
Suppose we have constructed a polynomial time reduction from problem $A$ to problem $B$. Which of the following can we infer from this fact? If the best algorithm for $B$ takes exponential time, there is no polynomial time algorithm for $A$ ... . If we don't know whether there is a polynomial time algorithm for $B$, there cannot be a polynomial time algorithm for $A$.
19
An undirected graph has $10$ vertices labelled $1, 2,\dots , 10$ and $37$ edges. Vertices $1, 3, 5, 7, 9$ have degree $8$ and vertices $2, 4, 6, 8$ have degree $7.$ What is the degree of vertex $10$ ? $5$ $6$ $7$ $8$
Twin primes are pairs of numbers $p$ and $p+2$ such that both are primes-for instance, $5$ and $7$, $11$ and $13$, $41$ and $43$. The Twin Prime Conjecture says that there are infinitely many twin primes. Let $\text{TwinPrime}(n)$ be a predicate that is true if $n$ ... $\exists m \cdot \forall n \cdot \text{TwinPrime}(n) \text{ implies }n \leq m$