TIFR 2017 Computer Science Questions

Recent questions tagged tifr2017

5 5 votes
1 1 answer
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A multivariate polynomial in $n$ variables with integer coefficients has a binary root if it is possible to assign each variable either 0 or 1, so that the polynomial eva...
19 19 votes
2 answers 2 answers
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Consider the following grammar $G$ with terminals $\{[, ]\}$, start symbol $S$, and non-terminals $\{A, B, C\}$:$$S \rightarrow AC \mid SS \mid AB$$$$C \rightarrow SB$$$...
18 18 votes
2 answers 2 answers
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For an undirected graph $G=(V, E)$, the line graph $G'=(V', E')$ is obtained by replacing each edge in $E$ by a vertex, and adding an edge between two vertices in $V'$ if...
67 67 votes
7 answers 7 answers
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An undirected graph is complete if there is an edge between every pair of vertices. Given a complete undirected graph on $n$ vertices, in how many ways can you choose a d...
34 34 votes
3 answers 3 answers
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Given that$B(x)$ means "$x$ is a bat",$F(x)$ means "$x$ is a fly", and$E(x, y)$ means "$x$ eats $y$",what is the best English translation of $$ \forall x(F(x) \rightarrow...
26 26 votes
2 answers 2 answers
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A vertex colouring of a graph $G=(V, E)$ with $k$ coulours is a mapping $c: V \rightarrow \{1, \dots , k\}$ such that $c(u) \neq c(v)$ for every $(u, v) \in E$. Consider ...
13 13 votes
6 answers 6 answers
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Which of the following regular expressions correctly accepts the set of all $0/1$-strings with an even (possibly zero) number of $1$s?$(10^*10^*)^*$$(0^*10^*1)^*$$0^*1(10...
21 21 votes
4 answers 4 answers
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For any natural number $n$, an ordering of all binary strings of length $n$ is a Gray code if it starts with $0^n$, and any successive strings in the ordering differ in e...
16 16 votes
2 answers 2 answers
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An array of $n$ distinct elements is said to be un-sorted if for every index $i$ such that $ 2 \leq i \leq n-1$, either $A[i] \text{max} \{A [i-1], A[i+1]\}$, or $A[i] <...
8 8 votes
1 answers 1 answer
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Consider the First Order Logic (FOL) with equality and suitable function and relation symbols. Which of the following is FALSE?Partial orders cannot be axiomatized in FOL...
21 21 votes
5 answers 5 answers
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Consider the following psuedocode fragment, where $y$ is an integer that has been initialized.int i=1 int j=1 while (i<10): j=j*i i=i+1 if (i==y): break end if end whileC...
19 19 votes
2 answers 2 answers
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Let $L$ be the language over the alphabet $\{1, 2, 3, (, )\}$ generated by the following grammar (with start symbol $S$, and non-terminals $\{A, B, C\}$):$ S \rightarrow ...
32 32 votes
5 answers 5 answers
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We have an implementation that supports the following operations on a stack (in the instructions below, $\mathsf{s}$ is the name of the stack).$\mathsf{isempty(s)}$ : ret...
5 5 votes
1 answers 1 answer
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Consider the following statements:Checking if a given $undirected$ graph has a cycle is in $\mathsf{P}$Checking if a given $undirected$ graph has a cycle is in $\mathsf{N...
39 39 votes
4 answers 4 answers
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A vertex colouring with three colours of a graph $G=(V, E)$ is a mapping $c: V \rightarrow \{R, G, B\}$ so that adjacent vertices receive distinct colours. Consider the f...
15 15 votes
4 answers 4 answers
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Let $T(a, b)$ be the function with two arguments (both nonnegative integral powers of 2) defined by the following recurrence:$ T(a, b) = T \left( \frac{a}{2}, b \right) +...
10 10 votes
4 answers 4 answers
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Consider the following game with two players, Aditi and Bharat. There are $n$ tokens in a bag. The two players know $n$, and take turns removing tokens from the bag. In e...
3 3 votes
1 1 answer
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A set of points $S \subseteq \mathbb{R}^2$ is convex if for any points $x, \: y \: \in S$, every point on the straight line joining $x$ and $y$ is also in $S$. For two se...
9 9 votes
1 answers 1 answer
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Consider the following program modifying an $n \times n$ square matrix $A$:for i=1 to n: for j=1 to n: temp=A[i][j]+10 A[i][j]=A[j][i] A[j][i]=temp-10 end for end forWhic...
26 26 votes
5 answers 5 answers
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Let $f \: \circ \: g$ denote function composition such that $(f \circ g)(x) = f(g(x))$. Let $f: A \rightarrow B$ such that for all $g \: : \: B \rightarrow A$ and $h \: :...
14 14 votes
3 answers 3 answers
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For a set $A$ define $P(A)$ to be the set of all subsets of $A$. For example, if $A = \{1, 2\}$ then $P(A) = \{ \emptyset, \{1, 2\}, \{1\}, \{ 2 \} \}$. Let $A \rightarro...
15 15 votes
2 answers 2 answers
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Consider the $majority$ function on three bits, $\textbf{maj}: \{0, 1\}^3 \rightarrow \{0, 1\}$ where $\textbf{maj}(x_1, x_2, x_3)=1$ if and only if $x_1+x_2+x_3 \geq 2$....
4 4 votes
2 answers 2 answers
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In a tutorial on geometrical constructions, the teacher asks a student to construct a right-angled triangle ABC where the hypotenuse BC is 8 inches and the length of the ...
15 15 votes
2 answers 2 answers
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Consider the sequence $S_0, S_1, S_2, \dots$ defined as follows: $S_0=0, \: S_1=1 \: $ and $S_n=2S_{n-1} + S_{n-2}$ for $n \geq 2$. Which of the following statements is F...
15 15 votes
2 answers 2 answers
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How many distinct words can be formed by permuting the letters of the word $\text{ABRACADABRA}?$$\frac{11!}{5! \: 2! \: 2!}$$\frac{11!}{5! \: 4! }$$11! \: 5! \: 2! \: 2!\...
19 19 votes
5 answers 5 answers
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How many distinct ways are there to split $50$ identical coins among three people so that each person gets at least $5$ coins?$3^{35}$$3^{50}-2^{50}$$\binom{35}{2}$$\bino...
24 24 votes
4 answers 4 answers
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Which of the following functions asymptotically grows the fastest as $n$ goes to infinity?$(\log \: \log \: n)!$$(\log \: \log \: n)^ {\log \: n}$$(\log \: \log \: n)^{\l...
5 5 votes
2 answers 2 answers
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On planet TIFR, the acceleration of an object due to gravity is half that on planet earth. An object on planet earth dropped from a height $h$ takes time $t$ to reach the...
6 6 votes
2 2 answers
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For vectors $x, \: y$ in $\mathbb{R}^n$, define the inner product $\langle x, y \rangle = \Sigma^n_{i=1} x_iy_i$, and the length of $x$ to be $\| x \| = \sqrt{\langle x, ...
10 10 votes
1 answers 1 answer
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A suitcase weighs one kilogram plus half of its weight. How much does the suitcase weigh?$1.3333$... kilograms$1.5$ kilograms$1.666$... kilograms$2$ kilogramscannot be de...
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