Chess parity problem
69748
Semi-Ambiguous Combinatorics Problem
136037
${n\choose 2} - {k\choose 2} = {n-k\choose 2} +k(n-k)$ Marked box or unmarked box
115934
What is the parity of permutation in the 15 puzzle?
50679
Induction problem: "if the group has at least one player who is better than Messi, then all the members of the group are better than Messi"
32181
A logic puzzle involving a balance.
152333
A problem based on pigeonhole
129352
Duality discrete math problem
132921
Counting problem, number of moves
123690
Olympiad question on Pigeonhole principle
19936
Coin Tossing Game Optimal Strategy
14783
A Number Theory problem (GCD)
134309
(0,1)-vector XOR problem
72417
Bipartite graphs
33373
Balanced orientation of infinite graphs
10272
A three-way duel (probability puzzle)
133097
How to utilize miniMax algorithm in Checkers game
60661
How to solve this combination problem quickly?