已知数列G(x)满足：G(1)=G(2)=G(3)=G(4)=1G(x)=G(x-1)+G(x-2)+G(x-3)+G(x-4)(x≥5)根据递推式写出求数列值

已知数列G(x)满足：G(1)=G(2)=G(3)=G(4)=1G(x)=G(x-1)+G(x-2)+G(x-3)+G(x-4)(x≥5)根据递推式写出求数列值的递归算法，问原始算法与采用openKe.Cn函数值缓存的算法时间复杂度分别为多少？
A.O(4^n);O(n)B.O(5^n);O(n^2)C.O(n^4);O(n^2)D.O(5^n);O(1)正确答案：O(4^n);O(n)