leetcode每日一题：830. 较大分组的位置

from typing import List


class Solution:
    def largeGroupPositions(self, s: str) -> List[List[int]]:
        if not s:
            return []

        result = []
        pre = s[0]
        count = 1
        for i in range(1, len(s)):
            if s[i] == pre:
                count += 1
            else:
                if count >= 3:
                    result.append([i-count, i-1])
                pre = s[i]
                count = 1
        if count >= 3:
            result.append([i-count+1, i])
        return result

s = Solution()
print(s.largeGroupPositions("abbxxxxzzy"))
print(s.largeGroupPositions("abc"))
print(s.largeGroupPositions("abcdddeeeeaabbbcd"))
print(s.largeGroupPositions("aaa"))

class Solution:
    def largeGroupPositions(self, s: str) -> List[List[int]]:
        ret = list()
        n, num = len(s), 1

        for i in range(n):
            # i == n-1 为最后一种测试用例的情况
            # 通过 s[i] 与 s[i+1] 对比，这样不需要像上面参考代码一样，从 1 开始初始化，也少了变量 pre 的记录
            if i == n - 1 or s[i] != s[i + 1]:
                if num >= 3:
                    ret.append([i - num + 1, i])
                num = 1
            else:
                num += 1

        return ret

# 作者：LeetCode-Solution
# 链接：https://leetcode-cn.com/problems/positions-of-large-groups/solution/jiao-da-fen-zu-de-wei-zhi-by-leetcode-so-fi3n/
# 来源：力扣（LeetCode）
# 著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。