בהינתן מחרוזת קלט ודפוס, בדוק אם התווים במחרוזת הקלט עוקבים אחר אותו סדר כפי שנקבע על ידי התווים הקיימים בדפוס. נניח שלא יהיו תווים כפולים בתבנית.
דוגמאות:
כיצד לשנות שם ספרייה בלינוקס
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.
דנו בשתי גישות לפתרון בעיה זו.
בדוק אם מחרוזת עוקבת אחר סדר התווים שהוגדרו על ידי דפוס או לא | סט 1
בדוק אם מחרוזת עוקבת אחר סדר התווים שהוגדרו על ידי דפוס או לא | סט 2
בגישה זו אנו מקצים תחילה תווית (או סדר) לתווים של דפוס. התוויות מוקצות בסדר הולך וגדל.
לדוגמה, התבנית 'gsr' מסומנת כדלקמן
'g' => 1 's' => 2 'r' => 3
זה אומר ש'g' יבוא קודם ואז 's' ואז 'r'
לאחר הקצאת תוויות לתווי דפוס אנו חוזרים על תווי מחרוזת. בזמן המעבר אנו עוקבים אחר התווית (או הסדר) של הדמות האחרונה שבה ביקרתם. אם התווית של התו הנוכחי קטנה מהתו הקודם נחזיר false. אחרת, אנו מעדכנים את התווית האחרונה. אם כל התווים עוקבים אחר הסדר נחזיר אמת.
להלן היישום
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(strpat) { 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>
תְפוּקָה
false
מורכבות זמן של תוכנית זו הוא עַל) עם רווח נוסף קבוע (תווית המערך היא בגודל קבוע 256).
gimp שמור כ-jpeg
מרחב עזר: O(256).