Leetcode 395. Longest Substring with at Least K repeating characters C #

Find the length of the longest substring T of a given string (consists of lowercase letters only) such that every Character in T appears no less than K times.

Example 1:

input:s = "Aaabb", k = 3output:3the longest substring is "AAA", and as ' a ' is repeated 3 times.

Example 2:

input:s = "Ababbc", k = 2output:5the longest substring is "ababb", as ' a ' are repeated 2 times and ' B ' is repeated 3 times.

Solution: map all characters in string s to a Hash Map and store the count of characters as values. If all characters occur to than Ktimes, then return the whole string length as result; if not, find the least occured character and split the string by this char, then call this function recursive Ly To get the max length out of all substrings. return the max.

1  Public classSolution {2      Public intLongestsubstring (stringSintk) {3dictionary<Char,int> map =Newdictionary<Char,int>();4         if(string. IsNullOrEmpty (s))5         {6             return 0;7         }8         intL =s.length;9          for(intI=0; i<l; i++)Ten         { One             if(map. ContainsKey (S[i])) A             { -map[s[i]]++; -             } the             Else -             { -Map. ADD (S[i],1); -             } +         } -         CharMinkey=map. Aggregate (p, r) = P.value < R.value?p:r). Key; +         if(map[minkey]>=k) A         { at             returnl; -         } -         string[] splitted =S.split (minkey); -         intMax =0; -         foreach(stringNinchsplitted) -         { in             intm =longestsubstring (n,k); -             if(m>max) to             { +Max =m; -             } the         } *         returnMax; $         Panax Notoginseng     } -}

Leetcode 395. Longest Substring with at Least K repeating characters C #