Cross and Cross
Time limit1sMemory limit128 MB
For a 1×n board where players alternately mark cells and the first to make three consecutive marks wins, decide the winner under optimal play for given n up to 2000.
- Level
Hard8 of 10
- Topics
- Game theory, Dynamic programming, Combinatorics
- Solved
- No attempts yet
Problem
Cross and Cross is a game played on a board of size 1 × n. The board is a single row of n unit cells (each 1 × 1), and two players alternate taking turns.
On your turn, you choose one empty cell and place an '×' mark in it.
If, as a result of a player's move, three horizontally consecutive cells all contain '×', that player wins immediately.
Given n, and assuming both players play optimally, determine which player wins. The player who moves first is called the first player.
Input
The first line contains an integer n. (3 ≤ n ≤ 2000)
Output
Print 1 if the first player (the one who moves first) wins, or 2 if the second player wins.