Educational Codeforces Round 145 (Rated for Div. 2)

Solutions for Educational Codeforces Round 145 (Rated for Div. 2) (contest 1809). 3/7 problems verified against sample I/O. Difficulty range: 800-2800.

7 items

Educational Codeforces Round 145 (Rated for Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 3/7 | Rating range: 800-2800 | Time: 13m 48s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Garland	800	implementation	3m 15s	✗
B	Points on Plane	1000	binary-search, greedy, math	1m 23s	✓
C	Sum on Subarrays	1500	constructive-algorithms, greedy, math	1m 53s	✗
D	Binary String Sorting	1800	constructive-algorithms, greedy	2m 18s	✓
E	Two Tanks	2400	binary-search, dp, implementation	1m 27s	✗
F	Traveling in Berland	2500	binary-search, data-structures, graphs	1m 48s	✗
G	Prediction	2800	combinatorics, dp, math	1m 44s	✓

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CF 1809G - Prediction

We are given a sorted list of participant ratings, and we are allowed to permute these participants into a line. After fixing a permutation, a sequential tournament is played: the first two players fight, then the winner immediately fights the third player in line, then the…

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CF 1809F - Traveling in Berland

We are asked to compute the minimum cost of a circular journey through Berland starting and ending at every city. Each city has a fuel station with a per-liter price, and traveling from city $i$ to city $i+1$ requires a fixed amount of fuel.

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CF 1809D - Binary String Sorting

We are given a binary string and want to transform it into a non-decreasing binary string. For binary strings, "sorted" means that all 0s appear before all 1s. Examples of sorted strings are 000111, 0, 111, and even the empty string. Two operations are available.

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CF 1809E - Two Tanks

We are given two containers with fixed capacities. The first can hold up to a units of water and the second up to b.

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CF 1809A - Garland

The symptom here is very specific: the program produces only one output (YES) instead of producing seven lines corresponding to the seven test cases. This is a structural bug in how the input loop is written or how the program reads multiple test cases.

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CF 1809C - Sum on Subarrays

We are asked to construct an integer array of length $n$, where each element must lie in a small bounded range, such that a very specific combinatorial property holds over all its subarrays. Every contiguous segment contributes a single value: the sum of its elements.

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CF 1809B - Points on Plane

We want to place n chips on integer lattice points of the plane. The cost of a chip at (x, y) is its Manhattan distance from the origin, The chips must satisfy one geometric restriction: every pair of chips must be more than 1 unit apart in Euclidean distance.