Ellenőrizze, hogy a karakterlánc követi-e a minta által meghatározott karakterek sorrendjét, vagy sem | 3. készlet
Adott egy bemeneti karakterlánc és egy minta ellenőrizze, hogy a bemeneti karakterlánc karakterei ugyanazt a sorrendet követik-e, mint amit a mintában jelen lévő karakterek határoznak meg. Tegyük fel, hogy nem lesznek ismétlődő karakterek a mintában.
Példák:
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.
Két megközelítést tárgyaltunk a probléma megoldására.
Ellenőrizze, hogy a karakterlánc követi-e a minta által meghatározott karakterek sorrendjét, vagy sem | 1. készlet
Ellenőrizze, hogy a karakterlánc követi-e a minta által meghatározott karakterek sorrendjét, vagy sem | 2. készlet
Ebben a megközelítésben először címkét (vagy sorrendet) rendelünk a minta karaktereihez. A címkék hozzárendelése növekvő sorrendben történik.
Például a „gsr” minta a következőképpen van megjelölve
'g' => 1 's' => 2 'r' => 3
Ez azt jelenti, hogy „g” lesz először, majd „s”, majd „r”
Miután a mintakarakterekhez címkéket rendeltünk, a karakterláncokon keresztül iterálunk. A bejárás során nyomon követjük az utoljára látogatott karakter címkéjét (vagy sorrendjét). Ha az aktuális karakter címkéje kisebb, mint az előző karakter, akkor false értéket adunk vissza. Ellenkező esetben frissítjük az utolsó címkét. Ha minden karakter a sorrendet követi, akkor igazat adunk vissza.
Alább a megvalósítás
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>
Kimenet
false
Idő összetettsége ennek a programnak az On) állandó extra szóközzel (a tömbcímke állandó méretű 256).
Segédtér: O(256).
