程序媛詹妮弗
终身学习

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.

题意:

给定字符串,求至多包含K种字符的最长子串

 

思路:

[leetcode]159. Longest Substring with At Most Two Distinct Characters至多包含两种字符的最长子串思路大体相同

      j
    j
S= “e c e b a”    and k = 2,  return 3  for "e c e"
    i             e-0          map.size <=2  move i 
      i           c-1          map.size <=2  move i 
        i         e-2(update)  map.size <=2  move i 
 ---------        b-3          map.size >2   get the length then move j 
          i  

 

代码:

 1 class Solution {
 2     public int lengthOfLongestSubstringKDistinct(String s, int k) {
 3         //corner 
 4         if(s.length() < k ) return s.length();
 5         // general
 6         HashMap<Character, Integer> map = new HashMap<>();
 7         int j = 0;
 8         int result = 0;
 9         for(int i = 0; i < s.length(); ){
10             char c = s.charAt(i);
11             if(map.size() <= k){
12                 map.put(c, i);
13                 i++;
14             }
15             if(map.size() > k){
16                 int leftMost = s.length();
17                 for(int n : map.values()){
18                     leftMost = Math.min(n, leftMost);
19                 }
20                
21                 map.remove(s.charAt(leftMost));
22                 j = leftMost + 1;
23             }
24             result = Math.max(i - j , result);
25           
26         }
27         return result; 
28         
29     }
30 }

 

posted on 2018-06-20 03:41  程序媛詹妮弗  阅读(119)  评论(0编辑  收藏  举报