Compruebe si la cadena sigue el orden de los caracteres definidos por un patrón o no | Conjunto 2
Dada una cadena de entrada y un patrón, verifique si los caracteres en la cadena de entrada siguen el mismo orden determinado por los caracteres presentes en el patrón. Suponga que no habrá caracteres duplicados en el patrón.
Se publica otra solución al mismo problema. aquí .
Ejemplos:
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.
La idea aquí es reducir la cadena dada al patrón dado. Para los caracteres dados en el patrón, solo mantenemos los caracteres correspondientes en la cadena. En la nueva cadena eliminamos los caracteres repetidos continuos. La cadena modificada debería entonces ser igual al patrón dado. Por último, comparamos la cadena modificada con el patrón dado y devolvemos verdadero o falso en consecuencia.
Ilustración:
str = 'bfbaeadeacc' pat[] = 'bac' 1) Remove extra characters from str (characters that are not present in pat[] str = 'bbaaacc' [f e and d are removed] 3) Removed consecutive repeating occurrences of characters str = 'bac' 4) Since str is same as pat[] we return true
A continuación se muestra la implementación de los pasos anteriores.
// C++ code for the above approach #include #include using namespace std ; bool followsPattern ( string str string pattern ) { // Insert all characters of pattern in a hash set unordered_set < char > patternSet ; for ( int i = 0 ; i < pattern . length (); i ++ ) { patternSet . insert ( pattern [ i ]); } // Build modified string (string with characters only from pattern are taken) string modifiedStr = str ; for ( int i = str . length () - 1 ; i >= 0 ; i -- ) { if ( patternSet . find ( str [ i ]) == patternSet . end ()) { modifiedStr . erase ( i 1 ); } } // Remove more than one consecutive occurrences of pattern characters from modified string for ( int i = modifiedStr . length () - 1 ; i > 0 ; i -- ) { if ( modifiedStr [ i ] == modifiedStr [ i - 1 ]) { modifiedStr . erase ( i 1 ); } } // After above modifications the length of modified string must be same as pattern length if ( pattern . length () != modifiedStr . length ()) { return false ; } // And pattern characters must also be same as modified string characters for ( int i = 0 ; i < pattern . length (); i ++ ) { if ( pattern [ i ] != modifiedStr [ i ]) { return false ; } } return true ; } int main () { string str = 'engineers rock' ; string pattern = 'er' ; cout < < 'Expected: true Actual: ' < < followsPattern ( str pattern ) < < endl ; str = 'engineers rock' ; pattern = 'egr' ; cout < < 'Expected: false Actual: ' < < followsPattern ( str pattern ) < < endl ; str = 'engineers rock' ; pattern = 'gsr' ; cout < < 'Expected: false Actual: ' < < followsPattern ( str pattern ) < < endl ; str = 'engineers rock' ; pattern = 'eger' ; cout < < 'Expected: true Actual: ' < < followsPattern ( str pattern ) < < endl ; return 0 ; } // This code is contributed by adityashatmfh
Java // Java program to check if characters of a string follow // pattern defined by given pattern. import java.util.* ; public class OrderOfCharactersForPattern { public static boolean followsPattern ( String str String pattern ) { // Insert all characters of pattern in a hash set Set < Character > patternSet = neHashSet <> (); for ( int i = 0 ; i < pattern . length (); i ++ ) patternSet . add ( pattern . charAt ( i )); // Build modified string (string with characters only from // pattern are taken) StringBuilder modifiedString = new StringBuilder ( str ); for ( int i = str . length () - 1 ; i >= 0 ; i -- ) if ( ! patternSet . contains ( modifiedString . charAt ( i ))) modifiedString . deleteCharAt ( i ); // Remove more than one consecutive occurrences of pattern // characters from modified string. for ( int i = modifiedString . length () - 1 ; i > 0 ; i -- ) if ( modifiedString . charAt ( i ) == modifiedString . charAt ( i - 1 )) modifiedString . deleteCharAt ( i ); // After above modifications the length of modified string // must be same as pattern length if ( pattern . length () != modifiedString . length ()) return false ; // And pattern characters must also be same as modified string // characters for ( int i = 0 ; i < pattern . length (); i ++ ) if ( pattern . charAt ( i ) != modifiedString . charAt ( i )) return false ; return true ; } // Driver program int main () { String str = 'engineers rock' ; String pattern = 'er' ; System . out . println ( 'Expected: true Actual: ' + followsPattern ( str pattern )); str = 'engineers rock' ; pattern = 'egr' ; System . out . println ( 'Expected: false Actual: ' + followsPattern ( str pattern )); str = 'engineers rock' ; pattern = 'gsr' ; System . out . println ( 'Expected: false Actual: ' + followsPattern ( str pattern )); str = 'engineers rock' ; pattern = 'eger' ; System . out . println ( 'Expected: true Actual: ' + followsPattern ( str pattern )); return 0 ; } }
Python3 # Python3 program to check if characters of # a string follow pattern defined by given pattern. def followsPattern ( string pattern ): # Insert all characters of pattern in a hash set patternSet = set () for i in range ( len ( pattern )): patternSet . add ( pattern [ i ]) # Build modified string (string with characters # only from pattern are taken) modifiedString = string for i in range ( len ( string ) - 1 - 1 - 1 ): if not modifiedString [ i ] in patternSet : modifiedString = modifiedString [: i ] + modifiedString [ i + 1 :] # Remove more than one consecutive occurrences # of pattern characters from modified string. for i in range ( len ( modifiedString ) - 1 0 - 1 ): if modifiedString [ i ] == modifiedString [ i - 1 ]: modifiedString = modifiedString [: i ] + modifiedString [ i + 1 :] # After above modifications the length of # modified string must be same as pattern length if len ( pattern ) != len ( modifiedString ): return False # And pattern characters must also be same # as modified string characters for i in range ( len ( pattern )): if pattern [ i ] != modifiedString [ i ]: return False return True # Driver Code if __name__ == '__main__' : string = 'engineers rock' pattern = 'er' print ( 'Expected: true Actual:' followsPattern ( string pattern )) string = 'engineers rock' pattern = 'egr' print ( 'Expected: false Actual:' followsPattern ( string pattern )) string = 'engineers rock' pattern = 'gsr' print ( 'Expected: false Actual:' followsPattern ( string pattern )) string = 'engineers rock' pattern = 'eger' print ( 'Expected: true Actual:' followsPattern ( string pattern )) # This code is contributed by # sanjeev2552
C# // C# program to check if characters of a string follow // pattern defined by given pattern. using System ; using System.Collections.Generic ; using System.Text ; class GFG { public static bool followsPattern ( String str String pattern ) { // Insert all characters of pattern in a hash set HashSet < char > patternSet = new HashSet < char > (); for ( int i = 0 ; i < pattern . Length ; i ++ ) patternSet . Add ( pattern [ i ]); // Build modified string (string with characters // only from pattern are taken) StringBuilder modifiedString = new StringBuilder ( str ); for ( int i = str . Length - 1 ; i >= 0 ; i -- ) if ( ! patternSet . Contains ( modifiedString [ i ])) modifiedString . Remove ( i 1 ); // Remove more than one consecutive occurrences of pattern // characters from modified string. for ( int i = modifiedString . Length - 1 ; i > 0 ; i -- ) if ( modifiedString [ i ] == modifiedString [ i - 1 ]) modifiedString . Remove ( i 1 ); // After above modifications the length of modified string // must be same as pattern length if ( pattern . Length != modifiedString . Length ) return false ; // And pattern characters must also be same // as modified string characters for ( int i = 0 ; i < pattern . Length ; i ++ ) if ( pattern [ i ] != modifiedString [ i ]) return false ; return true ; } // Driver program public static void Main ( String [] args ) { String str = 'engineers rock' ; String pattern = 'er' ; Console . WriteLine ( 'Expected: true Actual: ' + followsPattern ( str pattern )); str = 'engineers rock' ; pattern = 'egr' ; Console . WriteLine ( 'Expected: false Actual: ' + followsPattern ( str pattern )); str = 'engineers rock' ; pattern = 'gsr' ; Console . WriteLine ( 'Expected: false Actual: ' + followsPattern ( str pattern )); str = 'engineers rock' ; pattern = 'eger' ; Console . WriteLine ( 'Expected: true Actual: ' + followsPattern ( str pattern )); } } // This code is contributed by 29AjayKumar
JavaScript < script > // Javascript program to check if characters of a string follow // pattern defined by given pattern. function followsPattern ( str pattern ) { // Insert all characters of pattern in a hash set let patternSet = new Set (); for ( let i = 0 ; i < pattern . length ; i ++ ) patternSet . add ( pattern [ i ]); // Build modified string (string with characters only from // pattern are taken) let modifiedString = ( str ). split ( '' ); for ( let i = str . length - 1 ; i >= 0 ; i -- ) if ( ! patternSet . has ( modifiedString [ i ])) modifiedString . splice ( i 1 ); // Remove more than one consecutive occurrences of pattern // characters from modified string. for ( let i = modifiedString . length - 1 ; i > 0 ; i -- ) if ( modifiedString [ i ] == modifiedString [ i - 1 ]) modifiedString . splice ( i 1 ); // After above modifications the length of modified string // must be same as pattern length if ( pattern . length != modifiedString . length ) return false ; // And pattern characters must also be same as modified string // characters for ( let i = 0 ; i < pattern . length ; i ++ ) if ( pattern [ i ] != modifiedString [ i ]) return false ; return true ; } // Driver program let str = 'engineers rock' ; let pattern = 'er' ; document . write ( 'Expected: true Actual: ' + followsPattern ( str pattern ) + '
' ); str = 'engineers rock' ; pattern = 'egr' ; document . write ( 'Expected: false Actual: ' + followsPattern ( str pattern ) + '
' ); str = 'engineers rock' ; pattern = 'gsr' ; document . write ( 'Expected: false Actual: ' + followsPattern ( str pattern ) + '
' ); str = 'engineers rock' ; pattern = 'eger' ; document . write ( 'Expected: true Actual: ' + followsPattern ( str pattern ) + '
' ); // This code is contributed by rag2127 < /script>
Producción:
Expected: true Actual: true Expected: false Actual: false Expected: false Actual: false Expected: true Actual: true
Complejidad del tiempo: La complejidad temporal de las implementaciones anteriores es en realidad O (mn + n^2), ya que usamos deleteCharAt() para eliminar caracteres. Podemos optimizar la solución anterior para que funcione en tiempo lineal. En lugar de usar deleteCharAr() podemos crear una cadena vacía y agregarle solo los caracteres necesarios.
StringBuilder se utiliza para operar en una cadena de entrada. Esto se debe a que StringBuilder es mutable mientras que String es un objeto inmutable. Para crear una nueva cadena se necesita espacio O(n), por lo que el espacio adicional es O(n).
Hemos discutido dos enfoques más para resolver este problema.
Compruebe si la cadena sigue el orden de los caracteres definidos por un patrón o no | Conjunto 1
Compruebe si la cadena sigue el orden de los caracteres definidos por un patrón o no | Conjunto 3
