Find the length of the longest substringTof a given string (consists of lowercase letters only) such that every character inTappears no less thanktimes.
Example 1:?Input: ?= "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.
devide and conquer 雖然也是使用遞歸澈侠， 但是是二分式遞歸赐俗， 速度要快很多. 將字符串出現(xiàn)次數(shù)放到26個字符數(shù)組中徒坡， 查找個數(shù)小于k的顷霹， 分別算左邊和右邊的最大值，?
