Wincent DragonByte

2025 Winners

Champion and winner of €10,000: Kevin Sun (ksun48)
Runner-up and winner of €5,000: Andrew He (ecnerwala)
Third place and winner of €2,500: Dilhan Salgado (dnialh)

List of contests in the archive:

Current year:

Past year(s):

Contest: online2026

Writing credits

Problems for this round were created, prepared and tested by Mišo 'misof' Forišek, Truc Lam Bui ('Buj') and MišQo Farnbauer.

Final scoreboard:

Scoreboard

Problem B: Better Data Transfer

Problem statement
Solution writeup
B1.in: Input for B1.
B1.out: One possible output for B1.
B2.in: Input for B2.
B2.out: One possible output for B2.
B3.in: Input for B3.
B3.out: One possible output for B3.
B4.in: Input for B4.
B4.out: One possible output for B4.
B5.in: Input for B5.
B5.out: One possible output for B5.

Problem C: Chess Tournament

Problem statement
Solution writeup
C1.in: Input for C1.
C1.out: One possible output for C1.
C2.in: Input for C2.
C2.out: One possible output for C2.
C3.in: Input for C3.
C3.out: One possible output for C3.
C-checker.py: Checker in Python.
C-sol.py: Reference solution in Python.

Problem F: Forgetful BFS

Problem statement
Solution writeup
F1.in: Input for F1.
F1.out: Correct output for F1.
F2.in: Input for F2.
F2.out: Correct output for F2.
F3.in: Input for F3.
F3.out: Correct output for F3.
F4.in: Input for F4.
F4.out: Correct output for F4.
F5.in: Input for F5.
F5.out: Correct output for F5.
F-sol.py: Reference solution in Python (kinda slow).

Problem H: Hlohovec Space Program

Problem statement
Solution writeup
H1.in: Input for H1.
H1.out: One possible optimal output for H1.
H2.in: Input for H2.
H2.out: One possible optimal output for H2.
H3.in: Input for H3.
H3.out: One possible optimal output for H3.

Problem M: Martian Sieve

Problem statement
Solution writeup
M1.in: Input for M1.
M1.out: One possible output for M1.
M2.in: Input for M2.
M2.out: One possible output for M2.
M3.in: Input for M3.
M3.out: One possible output for M3.
M4.in: Input for M4.
M4.out: One possible output for M4.
M5.in: Input for M5.
M5.out: One possible output for M5.
M-sol.py: Reference solution in Python (alternate sol).
M-checker.py: Checker in Python.

Contest: qual2026

Writing credits

Problems for this round were created, prepared and tested by Mišo 'misof' Forišek, Samko 'Hodobox' Gurský, Truc Lam Bui ('Buj'), and Paulínka 'paulinia' Smolárová.

Final scoreboard:

Scoreboard

Problem S: Subtract First Digit

Problem statement
Solution writeup
S1.in: Input for S1.
S1.out: Correct output for S1.
S2.in: Input for S2.
S2.out: Correct output for S2.
S3.in: Input for S3.
S3.out: Correct output for S3.
S-sol.py: Full solution in Python that precomputes only one value.

Problem K: Kitchen Duty Roster

Problem statement
Solution writeup
K1.in: Input for K1.
K1.out: One correct output for K1.
K2.in: Input for K2.
K2.out: One correct output for K2.
K3.in: Input for K3.
K3.out: One correct output for K3.
K4.in: Input for K4.
K4.out: One correct output for K4.
K5.in: Input for K5.
K5.out: One correct output for K5.
K-sol.py: Full solution in Python.
K-checker.cpp: Checker in C++.

Problem R: Riffle Shuffles

Problem statement
Solution writeup
R0.in: Sample input file.
R_shuffle.py: Sample implementation of a riffle shuffle.
R1.in: Input for R1.
R1.out: Correct output for R1.
R2.in: Input for R2.
R2.out: Correct output for R2.
R-sol.py: Full solution in Python.
R-checker.py: Checker in Python that accepts a few mistakes.

Problem W: Water Slides

Problem statement
Solution writeup
W1.in: Input for W1.
W1.out: One correct output for W1.
W2.in: Input for W2.
W2.out: One correct output for W2.
W3.in: Input for W3.
W3.out: One correct output for W3.
W4.in: Input for W4.
W4.out: One correct output for W4.
W-sol.py: Full solution in Python.
W-checker.py: Output checker in Python.

Problem T: Table Drawing

Problem statement
Solution writeup
T1.in: Input for T1 (generated using 6300 commands).
T1.out: One output that scores 100 points for T1 (2443 commands).
T-sol.cpp: Solution in C++ (needs external ILP library).
T-checker.cpp: Checker in C++.

Contest: finals2025

Writing credits

Problems for this round were created, prepared and tested by Mišo 'misof' Forišek, Samko 'Hodobox' Gurský, Truc Lam Bui ('Buj'), Paulínka 'paulinia' Smolárová, Jakub 'Xellos' Šafin and Tomáš 'Tomi' Belan.

Final scoreboard:

Scoreboard

Problem E: Easy grid problem

Problem statement
Solution writeup
E1.in: The only input file.
E1.out: Output file (one possible).
E-checker.py: Checker in Python.

Problem M: Minimum edit area

Problem statement
Solution writeup
M1.in: Input file for subtask 1 (<=5 digits).
M1.out: One possible output file for subtask 1.
M2.in: Input file for subtask 2 (<=16 digits).
M2.out: One possible output file for subtask 2.
M3.in: Input file for subtask 3 (<=25 digits).
M3.out: One possible output file for subtask 3.
M4.in: Input file fr subtask 4 (<=1000 digits).
M4.out: One possible output file for subtask 4.
M-checker.py: Checker for subtasks 1, 2, 3.
M-checker4.py: Checker for subtask 4.

Problem A: Adjusting exit signs

Problem statement
Solution writeup
A1.in: Easy input file (area <= 25).
A1.out: Easy output file (one possible).
A2.in: Medium input file (area <= 1000).
A2.out: Medium output file (one possible).
A3.in: Hard input file (area <= 300,000).
A3.out: Hard output file (one possible).
A-checker.cpp: Checker in C++.
A-sol.cpp: Full solution in C++.

Problem F: Fewest ones

Problem statement
Solution writeup
F1.in: Input file for subtask 1 (t <= 10,000, r*c <= 21).
F1.out: Output file for subtask 1 (unique).
F2.in: Input file for subtask 2 (t <= 500, r <= 50).
F2.out: Output file for subtask 2 (unique).
F3.in: Input file for subtask 3 (t <= 10,000, r <= 1,000).
F3.out: Output file for subtask 3 (unique).
F4.in: Input file for subtask 4 (t <= 100, r <= 10^9).
F4.out: Output file for subtask 4 (unique).
F5.in: Input file for subtask 5 (t <= 10,000, r <= 10^17).
F5.out: Output file for subtask 5 (unique).
F-sol-dp.cpp: Solution for subtasks 1, 2, 3, in C++.
F-sol.cpp: Full solution in C++.

Problem L: Laser-protected museum

Problem statement
Solution writeup
L.out1: Quick ~63 point solution.
L.out2: Best author solution (~80 points).
L-checker.py: Checker in Python.

Contest: online2025

Writing credits

Problems for this round were created, prepared and tested by Mišo 'misof' Forišek, Samko 'Hodobox' Gurský, Truc Lam Bui ('Buj'), MišQo Farnbauer, and Jakub 'Xellos' Šafin.

Final scoreboard:

Scoreboard

Problem H: Heap

Problem statement
Solution writeup
H1.in: Input file.
H1.out: Output file (unique).
H_solution.py: Reference solution in Python

Problem D: Decode the digits

Problem statement
Solution writeup
D1.in: First input file.
D1.out: First output file (unique).
D2.in: Second input file.
D2.out: Second output file (unique).
D3.in: Third input file.
D3.out: Third output file (unique).
D4.in: Fourth input file.
D4.out: Fourth output file (unique).
D_solution.cpp: Reference solution in C++

Problem P: Politics

Problem statement
Solution writeup
P1.in: First input file.
P1.out: First output file (unique up to rounding).
P2.in: Second input file.
P2.out: Second output file (unique up to rounding).
P3.in: Third input file.
P3.out: Third output file (unique up to rounding).
P4.in: Fourth input file.
P4.out: Fourth output file (unique up to rounding).
P_solution.cpp: Solution in C++ (with gmp_floats for extra precision).

Problem S: Slow BFS

Problem statement
Solution writeup
S1.out: One possible tree that scores 100 points.
S_checker.cpp: Checker in C++

Problem W: Walk between spots

Problem statement
Solution writeup
W1.in: First input file.
W1.out: First output file (unique).
W2.in: Second input file.
W2.out: Second output file (unique).
W3.in: Third input file.
W3.out: Third output file (unique).
W4.in: Fourth input file.
W4.out: Fourth output file (unique).
W_solution.cpp: Reference solution in C++

Contest: qual2025

Writing credits

Problems for this round were created, prepared and tested by Mišo 'misof' Forišek, Samko 'Hodobox' Gurský, Truc Lam Bui ('Buj'), Mišo 'Žaba' Anderle, and Paulínka 'paulinia' Smolárová.

Final scoreboard:

Scoreboard

Problem N: Number pairs

Problem statement
Solution writeup
N1.in: Easy input file.
N1.out: Easy output file (one possible).
N2.in: Medium input file.
N2.out: Medium output file (one possible).
N3.in: Hard input file.
N3.out: Hard output file (one possible).
N-sol.py: Full solution in Python
N-checker.py: Checker in Python

Problem T: Tiling cheaply

Problem statement
Solution writeup
T1.in: Easy input file.
T1.out: Easy output file (one possible).
T2.in: Medium input file.
T2.out: Medium output file (one possible).
T3.in: Hard input file.
T3.out: Hard output file (one possible).
T-sol.cpp: Full solution in C++
T-checker.cpp: Checker in C++ (needs testlib.h)

Problem R: Rooks

Problem statement
Solution writeup
R1.in: Easy input file.
R1.out: Easy output file (unique).
R2.in: Medium input file.
R2.out: Medium output file (unique).
R3.in: Hard input file.
R3.out: Hard output file (unique).
R-sol.cpp: Full solution in C++
R-sol-slow.py: Easy subtask solution in Python

Problem B: Binary with a twist

Problem statement
Solution writeup
B1.in: Easy input file.
B1.out: Easy output file (unique).
B2.in: Medium input file.
B2.out: Medium output file (unique).
B3.in: Hard input file.
B3.out: Hard output file (unique).
B-sol1.cpp: Reference solution in C++
B-sol2.py: Slower but sufficient solution in Python

Problem K: Katamari

Problem statement
Solution writeup
K1.in: Input file.
K1.tsp: TSP file with the t_opt times for the checker.
K1.out: Output file (best paths found).
K-checker.py: Checker in Python.