Lua单词搜索：网格回溯的路径匹配

local function dfs(g, used, r, c, word, k)
    if k > #word then return true end
    if r < 1 or c < 1 or r > #g or c > #g[1] then
        return false
    end
    if used[r][c] or g[r][c] ~= word:sub(k, k) then
        return false
    end
    used[r][c] = true
    local found = dfs(g, used, r + 1, c, word, k + 1)
        or dfs(g, used, r - 1, c, word, k + 1)
        or dfs(g, used, r, c + 1, word, k + 1)
        or dfs(g, used, r, c - 1, word, k + 1)
    used[r][c] = false
    return found
end

local function exist(g, word)
    local used = {}
    for i = 1, #g do used[i] = {} end
    for i = 1, #g do
        for j = 1, #g[1] do
            if dfs(g, used, i, j, word, 1) then
                return true
            end
        end
    end
    return false
end
local g = {{"a", "b"}, {"c", "d"}}
local p = getplayerbyname("word01")
sendmsg(p, 1, tostring(exist(g, "abd")))