Skontrolujte, či reťazec nasleduje poradie znakov definovaných vzorom alebo nie | Súprava 3
Daný vstupný reťazec a vzor skontrolujú, či znaky vo vstupnom reťazci majú rovnaké poradie, aké určujú znaky prítomné vo vzore. Predpokladajme, že vo vzore nebudú žiadne duplicitné znaky.
Príklady:
Input: string = 'engineers rock' pattern = 'er'; Output: true All 'e' in the input string are before all 'r'. Input: string = 'engineers rock' pattern = 'egr'; Output: false There are two 'e' after 'g' in the input string. Input: string = 'engineers rock' pattern = 'gsr'; Output: false There are one 'r' before 's' in the input string.
Diskutovali sme o dvoch prístupoch k riešeniu tohto problému.
Skontrolujte, či reťazec nasleduje poradie znakov definovaných vzorom alebo nie | Set 1
Skontrolujte, či reťazec nasleduje poradie znakov definovaných vzorom alebo nie | Súprava 2
V tomto prístupe najprv priradíme označenie (alebo poradie) znakom vzoru. Štítky sa priraďujú v rastúcom poradí.
Napríklad vzor „gsr“ je označený nasledovne
'g' => 1 's' => 2 'r' => 3
Znamená to, že „g“ bude prvé, potom „s“ a potom „r“
Po priradení štítkov k znakom vzoru iterujeme cez reťazcové znaky. Pri prechádzaní sledujeme označenie (alebo poradie) poslednej navštívenej postavy. Ak je označenie aktuálneho znaku menšie ako predchádzajúci znak, vrátime hodnotu false. V opačnom prípade aktualizujeme posledný štítok. Ak všetky znaky dodržia poradie, vrátime hodnotu true.
Nižšie je uvedená implementácia
C++ // C++ program to find if a string follows order // defined by a given pattern. #include using namespace std ; const int CHAR_SIZE = 256 ; // Returns true if characters of str follow // order defined by a given ptr. bool checkPattern ( string str string pat ) { // Initialize all orders as -1 vector < int > label ( CHAR_SIZE -1 ); // Assign an order to pattern characters // according to their appearance in pattern int order = 1 ; for ( int i = 0 ; i < pat . length () ; i ++ ) { // give the pattern characters order label [ pat [ i ]] = order ; // increment the order order ++ ; } // Now one by check if string characters // follow above order int last_order = -1 ; for ( int i = 0 ; i < str . length (); i ++ ) { if ( label [ str [ i ]] != -1 ) { // If order of this character is less // than order of previous return false. if ( label [ str [ i ]] < last_order ) return false ; // Update last_order for next iteration last_order = label [ str [ i ]]; } } // return that str followed pat return true ; } // Driver code int main () { string str = 'engineers rock' ; string pattern = 'gsr' ; cout < < boolalpha < < checkPattern ( str pattern ); return 0 ; }
Java // Java program to find if a string follows order // defined by a given pattern. class GFG { static int CHAR_SIZE = 256 ; // Returns true if characters of str follow // order defined by a given ptr. static boolean checkPattern ( String str String pat ) { int [] label = new int [ CHAR_SIZE ] ; // Initialize all orders as -1 for ( int i = 0 ; i < CHAR_SIZE ; i ++ ) label [ i ] = - 1 ; // Assign an order to pattern characters // according to their appearance in pattern int order = 1 ; for ( int i = 0 ; i < pat . length (); i ++ ) { // give the pattern characters order label [ pat . charAt ( i ) ] = order ; // increment the order order ++ ; } // Now one by check if string characters // follow above order int last_order = - 1 ; for ( int i = 0 ; i < str . length (); i ++ ) { if ( label [ str . charAt ( i ) ] != - 1 ) { // If order of this character is less // than order of previous return false. if ( label [ str . charAt ( i ) ] < last_order ) return false ; // Update last_order for next iteration last_order = label [ str . charAt ( i ) ] ; } } // return that str followed pat return true ; } // Driver code public static void main ( String [] args ) { String str = 'engineers rock' ; String pattern = 'gsr' ; System . out . println ( checkPattern ( str pattern )); } } // This code is contributed by // sanjeev2552
Python3 # Python3 program to find if a string follows # order defined by a given pattern CHAR_SIZE = 256 # Returns true if characters of str follow # order defined by a given ptr. def checkPattern ( Str pat ): # Initialize all orders as -1 label = [ - 1 ] * CHAR_SIZE # Assign an order to pattern characters # according to their appearance in pattern order = 1 for i in range ( len ( pat )): # Give the pattern characters order label [ ord ( pat [ i ])] = order # Increment the order order += 1 # Now one by one check if string # characters follow above order last_order = - 1 for i in range ( len ( Str )): if ( label [ ord ( Str [ i ])] != - 1 ): # If order of this character is less # than order of previous return false if ( label [ ord ( Str [ i ])] < last_order ): return False # Update last_order for next iteration last_order = label [ ord ( Str [ i ])] # return that str followed pat return True # Driver Code if __name__ == '__main__' : Str = 'engineers rock' pattern = 'gsr' print ( checkPattern ( Str pattern )) # This code is contributed by himanshu77
C# // C# program to find if a string follows order // defined by a given pattern. using System ; class GFG { static int CHAR_SIZE = 256 ; // Returns true if characters of str follow // order defined by a given ptr. static bool checkPattern ( String str String pat ) { int [] label = new int [ CHAR_SIZE ]; // Initialize all orders as -1 for ( int i = 0 ; i < CHAR_SIZE ; i ++ ) label [ i ] = - 1 ; // Assign an order to pattern characters // according to their appearance in pattern int order = 1 ; for ( int i = 0 ; i < pat . Length ; i ++ ) { // give the pattern characters order label [ pat [ i ]] = order ; // increment the order order ++ ; } // Now one by check if string characters // follow above order int last_order = - 1 ; for ( int i = 0 ; i < str . Length ; i ++ ) { if ( label [ str [ i ]] != - 1 ) { // If order of this character is less // than order of previous return false. if ( label [ str [ i ]] < last_order ) return false ; // Update last_order for next iteration last_order = label [ str [ i ]]; } } // return that str followed pat return true ; } // Driver code public static void Main ( String [] args ) { String str = 'engineers rock' ; String pattern = 'gsr' ; Console . WriteLine ( checkPattern ( str pattern )); } } // This code is contributed by 29AjayKumar
JavaScript < script > // Javascript program to find if a string follows order // defined by a given pattern. let CHAR_SIZE = 256 ; // Returns true if characters of str follow // order defined by a given ptr. function checkPattern ( str pat ) { let label = new Array ( CHAR_SIZE ); // Initialize all orders as -1 for ( let i = 0 ; i < CHAR_SIZE ; i ++ ) label [ i ] = - 1 ; // Assign an order to pattern characters // according to their appearance in pattern let order = 1 ; for ( let i = 0 ; i < pat . length ; i ++ ) { // give the pattern characters order label [ pat [ i ]. charCodeAt ( 0 )] = order ; // increment the order order ++ ; } // Now one by check if string characters // follow above order let last_order = - 1 ; for ( let i = 0 ; i < str . length ; i ++ ) { if ( label [ str [ i ]. charCodeAt ( 0 )] != - 1 ) { // If order of this character is less // than order of previous return false. if ( label [ str [ i ]. charCodeAt ( 0 )] < last_order ) return false ; // Update last_order for next iteration last_order = label [ str [ i ]. charCodeAt ( 0 )]; } } // return that str followed pat return true ; } // Driver code let str = 'engineers rock' ; let pattern = 'gsr' ; document . write ( checkPattern ( str pattern )); // This code is contributed by rag2127 < /script>
Výstup
false
Časová zložitosť tohto programu je O(n) s konštantným priestorom navyše (označenie poľa má konštantnú veľkosť 256).
Pomocný priestor: O(256).
