VK Cup 2012 Wild-card Round 1

10 problems from VK Cup 2012 Wild-card Round 1 (contest 162), difficulty 1100-2000. 9/10 solutions verified against sample I/O.

10 items

VK Cup 2012 Wild-card Round 1

Special | 10 problems | 9/10 verified | Difficulty 1100-2000 | 16m 36s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Pentagonal numbers	1100	*special, implementation	842	3m 10s	✓
B	Binary notation	1800	*special	326	1m 20s	✓
C	Prime factorization	1800	*special	1,381	1m 16s	✓
D	Remove digits	1900	*special	232	1m 15s	✓
E	HQ9+	1800	*special	185	1m 9s	✓
F	Factorial zeros	1800	*special	229	1m 3s	✓
G	Non-decimal sum	2000	*special	88	1m 46s	✓
H	Alternating case	1800	*special	226	3m 11s
I	Truncatable primes	2000	*special	96	1m 22s	✓
J	Brackets	1800	*special	103	1m 4s	✓

Practice › Codeforces Solutions › VK Cup 2012 Wild-card Round 1 ›

CF 162A - Pentagonal numbers

We need to compute the n-th pentagonal number. Pentagonal numbers form a sequence generated by a direct mathematical formula: $$Pn = frac{3n^2 - n}{2}$$ The input contains a single integer n, and the output is the value of this formula for that position in the sequence.

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CF 162B - Binary notation

We are given a single positive integer and must print its representation in base 2. In other words, instead of expressing the number as powers of 10, we express it as powers of 2 using only digits 0 and 1.

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CF 162C - Prime factorization

We are asked to take a positive integer and express it as a product of prime numbers, showing each prime the number of times it appears in the factorization. For example, the number 245 can be expressed as 5 multiplied by 7 twice, so the output would be 577.

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CF 162D - Remove digits

We are given a single string containing printable ASCII characters. Some of those characters may be digits from '0' to '9'. The task is to remove every digit and print the remaining characters in their original order.

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CF 162E - HQ9+

The problem asks whether a program written in the joke language HQ9+ will produce any output. The program is a string containing between 1 and 100 printable ASCII characters. Only four instructions matter: "H", "Q", "9", and "+".

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CF 162F - Factorial zeros

The task is to determine how many trailing zeros appear at the end of the factorial of a given integer n. A factorial, denoted n!, is the product of all integers from 1 up to n.

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CF 162G - Non-decimal sum

We are given several integers written in an arbitrary base between 2 and 36. Digits above 9 are represented with uppercase letters, so in base 16 the digit sequence continues as A, B, C, D, E, F, and in larger bases it may continue up to Z.

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CF 162H - Alternating case

We are given a single string containing English letters in arbitrary capitalization. The task is to rewrite the string so that characters at odd positions become uppercase and characters at even positions become lowercase. The positions are counted starting from 1, not from 0.

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CF 162I - Truncatable primes

We are given a single integer and must decide whether it satisfies a very specific prime property. A number is considered truncatable if every suffix formed by repeatedly removing the leftmost digit is still prime.

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CF 162J - Brackets

We are given a string consisting solely of opening and closing round brackets. The task is to determine whether this sequence is balanced, meaning it could represent a correct arrangement of parentheses in a mathematical expression.