Minimum Recolors to Get K Consecutive Black Blocks
You are given a 0-indexed string blocks of length n, where blocks[i] is either 'W' or 'B', representing the color of the i^th block. The characters 'W' and 'B' denote the colors white and black, respectively.
You are also given an integer k, which is the desired number of consecutive black blocks.
In one operation, you can recolor a white block such that it becomes a black block.
Return the minimum number of operations needed such that there is at least one occurrence of k consecutive black blocks.
Example 1
Input
blocks = "WBBWWBBWBW", k = 7Output
3One way to achieve 7 consecutive black blocks is to recolor the 0th, 3rd, and 4th blocks so that blocks = "BBBBBBBWBW", and it can be shown this cannot be done in fewer than 3 operations.
Example 2
Input
blocks = "WBWBBBW", k = 2Output
0No changes need to be made, since 2 consecutive black blocks already exist.
Constraints
- n == blocks.length
- 1 <= n <= 100
- blocks[i] is either 'W' or 'B'.
- 1 <= k <= n