This is a cool problem that sounds very hard by becomes easy with two intuition sparks (and a little twinkle).
Description
In an array
A containing only 0s and 1s, a K-bit flip consists of choosing a (contiguous) subarray of length K and simultaneously changing every 0 in the subarray to 1, and every 1 in the subarray to 0.
Return the minimum number of
K-bit flips required so that there is no 0 in the array. If it is not possible, return -1.Example
Input: A = [0,0,0,1,0,1,1,0], K = 3
Output: 3
