Gitt en streng må vi sjekke om det er mulig å gjøre denne strengen til et palindrom etter å ha fjernet nøyaktig ett tegn fra denne.
Eksempler:
Input : str = abcba Output : Yes we can remove character ‘c’ to make string palindrome Input : str = abcbea Output : Yes we can remove character ‘e’ to make string palindrome Input : str = abecbea It is not possible to make this string palindrome just by removing one character
Vi kan løse dette problemet ved å finne posisjonen for misforhold. Vi begynner å sløyfe i strengen ved å holde to pekere i begge endene som går mot midtposisjon etter hver iterasjon, denne iterasjonen vil stoppe når vi finner en mismatch da det er tillatt å fjerne bare ett tegn, vi har to valg her
Ved mismatch, fjern enten tegn pekt av venstre peker eller fjern tegn pekt av høyre peker.
Vi vil sjekke begge tilfellene husk da vi har krysset like mange trinn fra begge sider denne midtstrengen skal også være et palindrom etter å ha fjernet ett tegn, så vi sjekker to understrenger, en ved å fjerne venstre tegn og en ved å fjerne høyre tegn, og hvis en av dem er palindrom, kan vi lage komplett strengpalindrom ved å fjerne tilsvarende tegn, og hvis begge understrengene ikke er en palindrom, er den ikke komplett. under gitt begrensning.
Implementering:
C++// C/C++ program to check whether it is possible to make // string palindrome by removing one character #include
// Java program to check whether // it is possible to make string // palindrome by removing one character import java.util.*; class GFG { // Utility method to check if // substring from low to high is // palindrome or not. static boolean isPalindrome(String str int low int high) { while (low < high) { if (str.charAt(low) != str.charAt(high)) return false; low++; high--; } return true; } // This method returns -1 if it is // not possible to make string a palindrome. // It returns -2 if string is already // a palindrome. Otherwise it returns // index of character whose removal can // make the whole string palindrome. static int possiblePalinByRemovingOneChar(String str) { // Initialize low and right // by both the ends of the string int low = 0 high = str.length() - 1; // loop until low and // high cross each other while (low < high) { // If both characters are equal then // move both pointer towards end if (str.charAt(low) == str.charAt(high)) { low++; high--; } else { /* * If removing str[low] makes the * whole string palindrome. We basically * check if substring str[low+1..high] * is palindrome or not. */ if (isPalindrome(str low + 1 high)) return low; /* * If removing str[high] makes the whole string * palindrome. We basically check if substring * str[low+1..high] is palindrome or not. */ if (isPalindrome(str low high - 1)) return high; return -1; } } // We reach here when complete string // will be palindrome if complete string // is palindrome then return mid character return -2; } // Driver Code public static void main(String[] args) { String str = 'abecbea'; int idx = possiblePalinByRemovingOneChar(str); if (idx == -1) System.out.println('Not Possible'); else if (idx == -2) System.out.println('Possible without ' + 'removing any character'); else System.out.println('Possible by removing' + ' character at index ' + idx); } } // This code is contributed by // sanjeev2552
# Python program to check whether it is possible to make # string palindrome by removing one character # Utility method to check if substring from # low to high is palindrome or not. def isPalindrome(string: str low: int high: int) -> bool: while low < high: if string[low] != string[high]: return False low += 1 high -= 1 return True # This method returns -1 if it # is not possible to make string # a palindrome. It returns -2 if # string is already a palindrome. # Otherwise it returns index of # character whose removal can # make the whole string palindrome. def possiblepalinByRemovingOneChar(string: str) -> int: # Initialize low and right by # both the ends of the string low = 0 high = len(string) - 1 # loop until low and high cross each other while low < high: # If both characters are equal then # move both pointer towards end if string[low] == string[high]: low += 1 high -= 1 else: # If removing str[low] makes the whole string palindrome. # We basically check if substring str[low+1..high] is # palindrome or not. if isPalindrome(string low + 1 high): return low # If removing str[high] makes the whole string palindrome # We basically check if substring str[low+1..high] is # palindrome or not if isPalindrome(string low high - 1): return high return -1 # We reach here when complete string will be palindrome # if complete string is palindrome then return mid character return -2 # Driver Code if __name__ == '__main__': string = 'abecbea' idx = possiblepalinByRemovingOneChar(string) if idx == -1: print('Not possible') else if idx == -2: print('Possible without removing any character') else: print('Possible by removing character at index' idx) # This code is contributed by # sanjeev2552
// C# program to check whether // it is possible to make string // palindrome by removing one character using System; class GFG { // Utility method to check if // substring from low to high is // palindrome or not. static bool isPalindrome(string str int low int high) { while (low < high) { if (str[low] != str[high]) return false; low++; high--; } return true; } // This method returns -1 if it is // not possible to make string a palindrome. // It returns -2 if string is already // a palindrome. Otherwise it returns // index of character whose removal can // make the whole string palindrome. static int possiblePalinByRemovingOneChar(string str) { // Initialize low and right // by both the ends of the string int low = 0 high = str.Length - 1; // loop until low and // high cross each other while (low < high) { // If both characters are equal then // move both pointer towards end if (str[low] == str[high]) { low++; high--; } else { /* * If removing str[low] makes the * whole string palindrome. We basically * check if substring str[low+1..high] * is palindrome or not. */ if (isPalindrome(str low + 1 high)) return low; /* * If removing str[high] makes the whole string * palindrome. We basically check if substring * str[low+1..high] is palindrome or not. */ if (isPalindrome(str low high - 1)) return high; return -1; } } // We reach here when complete string // will be palindrome if complete string // is palindrome then return mid character return -2; } // Driver Code public static void Main(String[] args) { string str = 'abecbea'; int idx = possiblePalinByRemovingOneChar(str); if (idx == -1) Console.Write('Not Possible'); else if (idx == -2) Console.Write('Possible without ' + 'removing any character'); else Console.Write('Possible by removing' + ' character at index ' + idx); } } // This code is contributed by shivanisinghss2110
<script> // JavaScript program to check whether // it is possible to make string // palindrome by removing one character // Utility method to check if // substring from low to high is // palindrome or not. function isPalindrome(str low high) { while (low < high) { if (str.charAt(low) != str.charAt(high)) return false; low++; high--; } return true; } // This method returns -1 if it is // not possible to make string a palindrome. // It returns -2 if string is already // a palindrome. Otherwise it returns // index of character whose removal can // make the whole string palindrome. function possiblePalinByRemovingOneChar(str) { // Initialize low and right // by both the ends of the string var low = 0 high = str.length - 1; // loop until low and // high cross each other while (low < high) { // If both characters are equal then // move both pointer towards end if (str.charAt(low) == str.charAt(high)) { low++; high--; } else { /* * If removing str[low] makes the * whole string palindrome. We basically * check if substring str[low+1..high] * is palindrome or not. */ if (isPalindrome(str low + 1 high)) return low; /* * If removing str[high] makes the whole string * palindrome. We basically check if substring * str[low+1..high] is palindrome or not. */ if (isPalindrome(str low high - 1)) return high; return -1; } } // We reach here when complete string // will be palindrome if complete string // is palindrome then return mid character return -2; } // Driver Code var str = 'abecbea'; var idx = possiblePalinByRemovingOneChar(str); if (idx == -1) document.write('Not Possible'); else if (idx == -2) document.write('Possible without ' + 'removing any character'); else document.write('Possible by removing' + ' character at index ' + idx); // this code is contributed by shivanisinghss2110 </script>
Produksjon
Not Possible
Tidskompleksitet: O(N)
Romkompleksitet: O(1)
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