面试编码问题 (OA)：计算 1 和 0 数组中大小为 k 的交替序列的数量

Question

Given an array consisting of 1s and 0s and an integer k find the number of alternating sequences of size k in the array. Treat the array as circular meaning the last index of the array follows onto the first index. Example:

array = [1,0,1,0,1,1], k = 4
solution_set = {1010, 0101}
result = 2

array = [1,0,1,0], k = 3
solution_set = {101, 010, 101(starting at 3rd index), 010(starting at 4th index}
result = 4

I did not get the answer fast enough, and had an unnecessarily complicated algorithm does anyone have a good way of doing this. Not even sure if dp is the best way of doing this.