LeetCode 1446: Consecutive Characters

Meta Data

#

Difficulty: easy First Attempt: 2022-08-24

• Submissions: Wrong Answer → Accepted

Approach

#

Extend the current run when a character equals the previous one, otherwise reset to 1 (the new character is itself a run of length 1), tracking the maximum. itertools.groupby also works.

My Attempts

#

Attempt 1 reset the run to 0 on a change, leaving out the new character: "baa" should be 2; it returned 1. Resetting to 1 passed.

Solution

#

class Solution:
    def maxPower(self, s: str) -> int:
        best = cur = 1
        for i in range(1, len(s)):
            cur = cur + 1 if s[i] == s[i - 1] else 1
            best = max(best, cur)
        return best

Complexity

#

Time O(n), space O(1).

Mistakes to Avoid

#

• Reset to 1, not 0.

Interview Explanation

#

In one pass I extend the run on equal neighbors and reset it to 1 otherwise, keeping the maximum. Time O(n), space O(1).