ICPC 2019-2020 North-Western Russia Regional Contest

13 problems from ICPC 2019-2020 North-Western Russia Regional Contest (contest 102411), difficulty -. 12/13 solutions verified against sample I/O.

13 items

ICPC 2019-2020 North-Western Russia Regional Contest

ICPC/IOI | 13 problems | 12/13 verified | Difficulty - | 1h 10m

#	Problem	Time	✓
A	Accurate Movement	5m 32s	✓
B	Bad Treap	1m 23s	✓
C	Cross-Stitch	5m 45s	✓
D	Double Palindrome	7m 29s	✓
E	Equidistant	2m 47s	✓
F	Foreach	2m 44s	✓
G	Golf Time	4m 27s	✓
H	High Load Database	2m 34s	✓
I	Ideal Pyramid	13m 5s	✓
J	Just the Last Digit	2m 54s	✓
K	King's Children	7m 56s
L	Lengths and Periods	12m 2s	✓
M	Managing Difficulties	1m 44s	✓

Practice › Codeforces Solutions › ICPC 2019-2020 North-Western Russia Regional Contest ›

CF 102411K - King's Children

We have an (n times m) grid. Some cells contain distinct uppercase letters, each letter representing one child's castle, while every other cell is empty. The task is to replace every empty cell by the lowercase letter of the child whose rectangular province contains that cell.

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CF 102411B - Bad Treap

A treap is simultaneously a binary search tree by its key (x) and a min-heap by its priority (y). In this problem the priority is not random: for every integer key (x), it is fixed as [ y=sin(x).

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CF 102411C - Cross-Stitch

The fabric is a rectangular grid of cells. Every cell marked X has to receive a cross on the front side, meaning both diagonals of that cell must be stitched.

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CF 102411M - Managing Difficulties

We have an array a describing the difficulties of problems published on consecutive days. We need to choose three indices i < j < k such that the middle difficulty is exactly halfway between the other two: [ aj-ai=ak-aj. ] Rearranging gives [ ai+ak=2aj.

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CF 102411J - Just the Last Digit

The hill can be viewed as a directed acyclic graph whose vertices are the spots (1,ldots,n). Every trail goes from a smaller index to a larger index, so the vertex numbering itself gives a topological order.

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CF 102411H - High Load Database

We have an array of transactions (a1,a2,ldots,an), where transaction (i) contains (ai) queries. We must partition this array into consecutive groups.

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CF 102411F - Foreach

We have an integer array a of length n, and we want to transform it into a target array b. The only instructions we are allowed to print are two special foreach loops.

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CF 102411E - Equidistant

The railroad network is a tree. Each city is a vertex, each railroad is an edge, and traveling across one edge takes one hour. A subset of the vertices contains the cities where the teams are located.

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CF 102411L - Lengths and Periods

We have a string w of length at most 200000. We want to find the most repetitive substring inside it, where the repetition is allowed to stop halfway through the next copy. Suppose a substring has period p and length L. Its exponent is L / p.

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CF 102411G - Golf Time

The golf course is an axis-aligned rectangle of width w and height h. A ball starts at an integer point (x0, y0) strictly inside the course and moves northeast, increasing both coordinates by exactly one inch per second.

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CF 102411D - Double Palindrome

We need to count strings over an alphabet of size (k), considering every non-empty length from (1) through (n). A string is valid if it is itself a palindrome or can be split into two palindromes. The two pieces may have different lengths and may even be identical.

Practice › Codeforces Solutions › ICPC 2019-2020 North-Western Russia Regional Contest ›

CF 102411A - Accurate Movement

We have a box of length n containing two bars on parallel rails. The short bar has length a, the long bar has length b, with a < b. The long bar carries a stopper at each end, and the short bar must remain completely between those two stoppers.

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CF 102411I - Ideal Pyramid

We need to choose an integer center (X, Y) and an integer height H for an axis-aligned square pyramid. Because every side has slope exactly 45°, moving one unit horizontally or vertically away from the center lowers the pyramid by exactly one unit.