Odd length sub - string
else { countt [ str [ end ] ] ++ ; unordered_map < int , int > c ( countt . begin ( ) , countt . end ( ) ) ; int length = maxPal ( str , c , start , end + 1 ) ; countt [ str [ end ] ] -- ; countt [ str [ start ] ] -- ; return max ( length , maxPal ( str , countt , start + 1 , end ) ) ; } } }