:-)

inline int FloydCycleFind ( int x0 ){ x0 %= m ; if ( ! k ) return x0 ; int hare = f ( f ( x0 )), tortoise = f ( x0 ); while ( tortoise != hare ){ hare = f ( f ( hare )); tortoise = f ( tortoise ); } int mu = 0 ; hare = x0 ; while ( tortoise != hare ){ hare = f ( hare ); tortoise = f ( tortoise ); mu ++ ; if ( mu == k ) return hare ; } k -= mu ; int lambda = 1 ; hare = f ( tortoise ); while ( hare != tortoise ) hare = f ( hare ), lambda ++ ; k %= lambda ; while ( k ) tortoise = f ( tortoise ), k -- ; return tortoise ; } https://toph.co/p/not-my-fault

https://www.geeksforgeeks.org/find-the-number-occurring-odd-number-of-times/