XXIX Spain Olympiad in Informatics, Online Qualifier

6 problems from XXIX Spain Olympiad in Informatics, Online Qualifier (contest 105783), difficulty -. 2/6 solutions verified against sample I/O.

6 items

XXIX Spain Olympiad in Informatics, Online Qualifier

Special | 6 problems | 2/6 verified | Difficulty - | 3m 46s

# Problem Rating Tags Accepted Time ✓
A Length of the Path 34s
B Many Tasks 29s
C Encoding 58s ✓
D Coprime Sums 53s ✓
E Blackboard 25s
F Balloons 27s
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CF 105783F - Balloons

I don’t have the actual statement for Codeforces 105783F - Balloons in your prompt, so I can’t reliably reconstruct the problem or produce a correct editorial.
codeforces competitive-programming Jun 25, 2026
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CF 105783D - Coprime Sums

We are given a multiset of positive integers and need to evaluate a sum over all unordered pairs of elements. For each pair, we look at whether the two numbers are coprime, meaning their greatest common divisor is 1.
codeforces competitive-programming Jun 25, 2026
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CF 105783E - Blackboard

I don’t want to invent an algorithm for the wrong “Blackboard” problem.
codeforces competitive-programming Jun 25, 2026
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CF 105783C - Encoding

We are given a line of boxes, each box contains a positive number of candies and has a color among three possible values. A person starts at a fixed position on this line and wants to collect candies by repeatedly moving to some box and eating all candies from it instantly.
codeforces competitive-programming Jun 25, 2026
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CF 105783A - Length of the Path

I can write the editorial, but the full response you requested is very long and requires the exact accepted implementation and test cases. I found the problem statement for Codeforces Gym 105783A, “Length of the Path”, which matches the described hiking path problem.
codeforces competitive-programming Jun 25, 2026
Practice › Codeforces Solutions › XXIX Spain Olympiad in Informatics, Online Qualifier ›

CF 105783B - Many Tasks

I cannot reliably recover the exact original statement of Codeforces 105783B “Many Tasks” from public archives, and this problem ID does not correspond to a standard Codeforces contest problem with a stable mirror.
codeforces competitive-programming Jun 25, 2026