Проверите да ли стринг прати редослед знакова дефинисаних шаблоном или не | Сет 3
Дати улазни низ и образац, проверите да ли знакови у улазном низу прате исти редослед који одређују карактери присутни у шаблону. Претпоставимо да у обрасцу неће бити дуплираних знакова.
Примери:
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.
Разговарали смо о два приступа за решавање овог проблема.
Проверите да ли стринг прати редослед знакова дефинисаних шаблоном или не | Сет 1
Проверите да ли стринг прати редослед знакова дефинисаних шаблоном или не | Сет 2
У овом приступу прво додељујемо ознаку (или редослед) знаковима шаблона. Ознаке се додељују растућим редоследом.
На пример, образац 'гср' је означен на следећи начин
'g' => 1 's' => 2 'r' => 3
То значи да ће 'г' бити прво, па 'с' па 'р'
Након додељивања ознака знаковима шаблона, понављамо низ знакова низа. Током преласка пратимо ознаку (или редослед) последњег посећеног карактера. Ако је ознака тренутног знака мања од претходног знака, враћамо фалсе. У супротном ажурирамо последњу етикету. Ако сви знакови следе редослед, враћамо тачно.
Испод је имплементација
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>
Излаз
false
Временска сложеност овог програма је О(н) са константним додатним простором (ознака низа је константне величине 256).
Помоћни простор: О(256).
