Decreasing-Increasing Order drill

# Decreasing-increasing order drill

function IsInDecreasingOrder(dx::Array{Int64, 1})
    OK = false

    for d in dx
        if d > 0; return false; end
        if d < 0; OK = true; end
    end

    return OK
end

function IsInIncreasingOrder(dx::Array{Int64, 1})
    OK = false

    for d in dx
        if d < 0; return false; end
        if d > 0; OK = true; end
    end

    return OK
end

function main(x::Array{Int64, 1})
    dx = diff(x)

    for i = 1:(length(dx)-1)
        dx1 = dx[1:i]

        if IsInDecreasingOrder(dx1)
            dx2 = dx[(i+1):end]
            if IsInIncreasingOrder(dx2); return true, x[i]; end
        end
    end

    return false, NaN
end