Lua八皇后：按行回溯的三线剪枝

local function conflict(pos, row, col)
    for r = 1, row - 1 do
        local c = pos[r]
        if c == col
            or math.abs(r - row) == math.abs(c - col) then
            return true
        end
    end
    return false
end

local total = 0
local pos = {}
local function solve(row)
    if row > 8 then
        total = total + 1
        return
    end
    for col = 1, 8 do
        if not conflict(pos, row, col) then
            pos[row] = col
            solve(row + 1)
        end
    end
end
solve(1)
local p = getplayerbyname("queen01")
sendmsg(p, 1, "八皇后共 " .. total .. " 个解")