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.

 

这道题是之前那道的拓展，而且那道题中的解法一和解法二直接将2换成k就行了，具体讲解请参考之前那篇博客：

 

解法一：

class Solution {public:    int lengthOfLongestSubstringKDistinct(string s, int k) {        int res = 0, left = 0;        unordered_map
     
       m;        for (int i = 0; i < s.size(); ++i) {            ++m[s[i]];            while (m.size() > k) {                if (--m[s[left]] == 0) m.erase(s[left]);                ++left;            }            res = max(res, i - left + 1);        }        return res;    }};
     

 

具体讲解请参考之前那篇博客，参见代码如下：

 

解法二：

class Solution {public:    int lengthOfLongestSubstringKDistinct(string s, int k) {        int res = 0, left = 0;        unordered_map
     
       m;        for (int i = 0; i < s.size(); ++i) {            m[s[i]] = i;            while (m.size() > k) {                if (m[s[left]] == left) m.erase(s[left]);                ++left;            }            res = max(res, i - left + 1);        }        return res;    }};
     

 

类似题目：