【进阶实战】Lua广度优先：沙巴克传送网的最短跳数

local visited = {}
local function walk(node)
    visited[node] = true
    for _, nxt in ipairs(NET[node] or {}) do
        if not visited[nxt] then walk(nxt) end  -- 只走不数跳数
    end
end

local function hops(from, to)
    local queue, seen = {{node = from, d = 0}}, {[from] = true}
    while #queue > 0 do
        local cur = table.remove(queue, 1)
        if cur.node == to then return cur.d end
        for _, nxt in ipairs(NET[cur.node] or {}) do
            if not seen[nxt] then
                seen[nxt] = true
                queue[#queue + 1] = {node = nxt, d = cur.d + 1}
            end
        end
    end
    return -1
end
sendmsg(actor, 1, "沙巴克传送网最短 "
    .. hops("盟重", "沙城") .. " 跳")