Given a string, find the length of the longest substring T that contains at most k distinct characters.
Example 1:
Input: s = "eceba", k = 2
Output: 3
Explanation: T is "ece" which its length is 3.
Example 2:
Input: s = "aa", k = 1
Output: 2
Explanation: T is "aa" which its length is 2.
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;
}
};
类似题目：
Longest Substring with At Most Two Distinct Characters
参考资料：
https://leetcode.com/problems/longest-substring-with-at-most-k-distinct-characters/
LeetCode All in One 题目讲解汇总(持续更新中…)
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