2379. Minimum Recolors to Get K Consecutive Black Blocks
Easy
542
15

You are given a 0-indexed string `blocks` of length `n`, where `blocks[i]` is either `'W'` or `'B'`, representing the color of the `ith` 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 = 7
Output: 3
Explanation:
One way to achieve 7 consecutive black blocks is to recolor the 0th, 3rd, and 4th blocks
so that blocks = "BBBBBBBWBW".
It can be shown that there is no way to achieve 7 consecutive black blocks in less than 3 operations.
Therefore, we return 3.
```

Example 2:

```Input: blocks = "WBWBBBW", k = 2
Output: 0
Explanation:
No changes need to be made, since 2 consecutive black blocks already exist.
Therefore, we return 0.
```

Constraints:

• `n == blocks.length`
• `1 <= n <= 100`
• `blocks[i]` is either `'W'` or `'B'`.
• `1 <= k <= n`
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