LeetCode 340. Longest Substring with At Most K Distinct Characters

原题链接在这里：https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/

题目：

Given a string, find the length of the longest substring T that contains at most k distinct characters.

For example, Given s = “eceba” and k = 2,

T is "ece" which its length is 3.

题解：

类似Longest Substring with At Most Two Distinct Characters.

2变成k即可.

Time Complexity: O(n), n = s.length(). Space: O(1), map size.

AC Java:

public class Solution {
    public int lengthOfLongestSubstringKDistinct(String s, int k) {
        int res = 0;
        int [] map = new int[256];
        int walker = 0;
        int runner = 0;
        int count = 0;
        while(runner < s.length()){
            if(map[s.charAt(runner++)]++ == 0){
                count++;
            }
            while(count > k){
                if(map[s.charAt(walker++)]-- == 1){
                    count--;
                }
            }
            res = Math.max(res, runner - walker);
        }
        return res;
    }
}

跟上Longest Repeating Character Replacement.