题目链接: https://leetcode.com/problems/longest-substring-with-at-least-k-repeating-characters/
题目描述:
Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every character in T appears no less than k times.
Example 1:
Input:
s = "aaabb", k = 3
Output:
3
The longest substring is "aaa", as 'a' is repeated 3 times.
Example 2:
Input:
s = "ababbc", k = 2
Output:
5
The longest substring is "ababb", as 'a' is repeated 2 times and 'b' is repeated 3 times.
题目大意:
在字符串s中找出最长的子串T,T中的每个字符在T中出现次数不少于k。
思路:
- 字符串s长度小于k,不存在T;
- 如果一个字符在s中出现的次数少于k次,那么在所有s的子串中都不存在包含该字符的子串T,那就以该字符为界,在所有不包含该字符的字符串中寻找T。
- 如果s中每个字符的出现次数都大于k,返回s。
class Solution:
def longestSubstring(self, s, k):
"""
:type s: str
:type k: int
:rtype: int
"""
if len(s)<k:
return 0
for i in set(s):
if (s.count(i)>0 and s.count(i)<k):
return max(self.longestSubstring(t, k) for t in s.split(i))
return len(s)
ps. 这个python代码…真好看!