| Difficulty: | Hard |
| Topics: | game |
A tic-tac-toe board is represented by a two dimensional vector. X is represented by :x, O is represented by :o, and empty is represented by :e. A player wins by placing three Xs or three Os in a horizontal, vertical, or diagonal row. Write a function which analyzes a tic-tac-toe board and returns :x if X has won, :o if O has won, and nil if neither player has won.
(= nil (__ [[:e :e :e]
[:e :e :e]
[:e :e :e]]))
(= :x (__ [[:x :e :o]
[:x :e :e]
[:x :e :o]]))
(= :o (__ [[:e :x :e]
[:o :o :o]
[:x :e :x]]))
(= :x (__ [[:x :e :e]
[:o :x :e]
[:o :e :x]]))
(= :o (__ [[:x :e :o]
[:x :o :e]
[:o :e :x]]))
(= nil (__ [[:x :o :x]
[:x :o :x]
[:o :x :o]]))
解长度：178
(fn [m]
(let [a (concat (apply map vector m) (seq m)
((fn [x] (let [g #(get-in x %) d (g [1 1])]
(seq [[(g [0 0]) d (g [2 2])] [(g [0 2]) d (g [2 0])]]))) m)) h (fn [k] (some #(every? #{k} %) a))]
(if (h :x)
:x
(if (h :o)
:o
nil))))
基本思路，先将输入产生8个vector，3横，3纵以及两个对角线，所以
(apply map vector m)就是生成3纵； (seq m)就是3横，
((fn cro [x] (let [g #(get-in x %) d (g [1 1])] (seq [[(g [0 0]) d (g [2 2])] [(g [0 2]) d (g [2 0])]]))) m)) 就是两个对角线。
user=>(def input[[:x :o :x] [:x :o :x] [:o :x :o]])user=>(apply map vector input); ([:x :x :o] [:o :o :x] [:x :x :o])user=>(seq input); ([:x :o :x] [:x :o :x] [:o :x :o])user=>(cro input); ([:x :o :o] [:x :o :o])user=>(some #(every? #{:x} %) ‘([:x :x :o] [:o :o :x] [:x :x :o])); niluser=>(some #(every? #{:x} %) ‘([:x :x :x] [:o :o :x] [:x :x :o])); trueuser=>(some #(every? #{:x} %) ‘([:x :x :o] [:o :o :o] [:x :x :o])); nil
最后整理，函数匿名，已经尽可能缩短字数。