Submission #694231

---

Source Code Expand

function main()
    R, C = io.read "n", io.read "n"
    sy, sx = io.read "n", io.read "n"
    gy, gx = io.read "n", io.read "n"
    io.read "l"
    c = { }
    for i = 1, R do
        c[i] = { }
        for j = 1, C do
            c[i][j] = io.read(1) == "." and math.huge or nil
        end
        io.read "l"
    end
    q = Queue()
    q:offer { sy, sx }
    c[sy][sx] = 0
    for e in q:coroPoll() do
        if e[1] == gy and e[2] == gx then
            break
        end
        for _, d in pairs(delta) do
            local y, x = e[1] + d[1], e[2] + d[2]
            if c[y][x] == math.huge then
                c[y][x] = c[e[1]][e[2]] + 1
                q:offer { y, x }
            end
        end
    end
    print(c[gy][gx])
end

delta = { { 0, 1 }, { 0, -1 }, { 1, 0 }, { -1, 0 } }

function Queue()
    local o = { }
    local t = { }
    local front = 1
    local rear = 1

    function o:offer(e)
        t[front] = e
        front = front + 1
    end

    function o:poll()
        if rear == front then
            return nil
        end
        local e = t[rear]
        t[rear] = nil
        rear = rear + 1
        return e
    end

    function o:peek()
        return t[rear]
    end

    function o:coroPoll()
        return coroutine.wrap(
            function()
                while rear ~= front do
                    coroutine.yield(self:poll())
                end
            end
        )
    end

    return o
end

main()

Submission Info

Judge Result