[LeetCode] 2379. Minimum Recolors to Get K Consecutive Black Blocks (Python)

 

난이도: Easy

Problem Description

---

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.

 

Problem Example

---

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

 

✏️ Solution

---

class Solution:
    def minimumRecolors(self, blocks: str, k: int) -> int:
        n = len(blocks)

        answer = n+1
        for i in range(n-k+1):
            answer = min(answer, blocks[i:i+k].count('W'))
            if answer == 0:
                return 0
        
        return answer

 

blocks에서 k의 길이를 갖는 substring에서 'W' 갯수를 세고 그 갯수가 제일 작은 값이 답이 된다.

 

예를 들어 blocks는 "WBBWWBBWBW"이고 k=7이라면, 아래 그림과 같이 구할 수 있다.

 

⚙️ Runtime & Memory

---

 

 

---

문제: 2379. Minimum Recolors to Get K Consecutive Black Blocks

 

깃허브: github

algorithmPractice/LeetCode/2463-minimum-recolors-to-get-k-consecutive-black-blocks at main · laewonJeong/algorithmPractice