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340. Longest Substring with At Most K Distinct Characters
Description
Given a string s and an integer k, return the length of the longest substring of s that contains at most k distinct characters.
Example 1:
Input: s = "eceba", k = 2 Output: 3 Explanation: The substring is "ece" with length 3.
Example 2:
Input: s = "aa", k = 1 Output: 2 Explanation: The substring is "aa" with length 2.
Constraints:
1 <= s.length <= 5 * 1040 <= k <= 50
Solutions
Same as 159 Longest Substring with At Most Two Distinct Characters
- change from
2tok
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class Solution { public int lengthOfLongestSubstringKDistinct(String s, int k) { Map<Character, Integer> cnt = new HashMap<>(); int n = s.length(); int ans = 0, j = 0; for (int i = 0; i < n; ++i) { char c = s.charAt(i); cnt.put(c, cnt.getOrDefault(c, 0) + 1); while (cnt.size() > k) { char t = s.charAt(j); cnt.put(t, cnt.getOrDefault(t, 0) - 1); if (cnt.get(t) == 0) { cnt.remove(t); } ++j; } ans = Math.max(ans, i - j + 1); } return ans; } } -
class Solution { public: int lengthOfLongestSubstringKDistinct(string s, int k) { unordered_map<char, int> cnt; int n = s.size(); int ans = 0, j = 0; for (int i = 0; i < n; ++i) { cnt[s[i]]++; while (cnt.size() > k) { if (--cnt[s[j]] == 0) { cnt.erase(s[j]); } ++j; } ans = max(ans, i - j + 1); } return ans; } }; -
class Solution: def lengthOfLongestSubstringTwoDistinct(self, s: str) -> int: cnt = Counter() # or, cnt = defaultdict(int) ans = i = 0 for j, c in enumerate(s): cnt[c] += 1 while len(cnt) > k: cnt[s[i]] -= 1 if cnt[s[i]] == 0: cnt.pop(s[i]) i += 1 ans = max(ans, j - i + 1) return ans -
func lengthOfLongestSubstringKDistinct(s string, k int) (ans int) { cnt := map[byte]int{} j := 0 for i := range s { cnt[s[i]]++ for len(cnt) > k { cnt[s[j]]-- if cnt[s[j]] == 0 { delete(cnt, s[j]) } j++ } ans = max(ans, i-j+1) } return }