[LeetCode] Longest Substring with At Most K Distinct Characters 最多有K个不同字符的最长子串...

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Longest Substring with At Most Two Distinct Characters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<char, int> 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Longest Substring with At Most Two Distinct Characters，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<char, int> 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;}
};

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Longest Substring with At Most Two Distinct Characters

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