受井字棋和五子棋均有先手必赢策略的启发,本文针对落子不受限制的普通四子棋进行研究,归纳并证明了普通四子棋先手有必赢策略的最小棋盘大小为 6×5, 并给出落子规则和先手的必赢策略; 证明了棋盘大小为 5×5 时双方每步均采取最佳位置时必然平局, 发现普通四子棋变化较少, 可玩性不强. 针对更加普遍的四子棋形式,即棋子必须落在最低行或正下方有子的格子上方的屏风式四子棋, 对已有的在棋盘为偶数行情况下先手必赢的策略进行改进, 探索棋盘为奇数行情况下的输赢情况, 给出列数无限情况下后手的平局策略,并提出未来可研究的方向. 

Studies have shown that both tic-tac-toe and gobang have the first-mover-win strategies. This paper researches the ordinary connect four whose fall is not restricted. This article concludes and proves that the first-mover of the ordinary connect four has the winning strategies in the minimum board size of 6×5, and gives the moving rules and the winning strategies of the first mover. Also, this paper proves that in the board size of 5 × 5, when both sides take the best position for each step, the result must be a draw. According to the previous research results, finding that ordinary connect four changes less and its playability is not strong. Aiming at the more common form of connect four, i.e. the chess must fall on the lowest row or the top of the grid with the chess right below, this article improves the existing strategies that the first player must win when the board is even numbered, explores the winning and losing situation when the board is odd numbered, and presents the draw strategies of the second mover when the number of rows is infinite. What’s more, putting forward the future research direction.