Gegeven een string moeten we controleren of het mogelijk is om van deze string een palindroom te maken nadat we hier precies één teken uit hebben verwijderd.
Voorbeelden:
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
We kunnen dit probleem oplossen door de positie van de mismatch te vinden. We beginnen de string in een lus te plaatsen door aan beide uiteinden twee aanwijzers te houden die na elke iteratie naar de middenpositie gaan. Deze iteratie stopt wanneer we een mismatch vinden, aangezien het toegestaan is om slechts één teken te verwijderen. We hebben hier twee keuzes
Bij een mismatch verwijdert u het teken dat door de linkeraanwijzer wordt aangewezen, of verwijdert u het teken dat door de rechteraanwijzer wordt aangewezen.
We zullen beide gevallen controleren, onthoud, aangezien we van beide kanten een gelijk aantal stappen hebben doorlopen, zou deze middelste reeks ook een palindroom moeten zijn na het verwijderen van één teken, dus we controleren twee substrings, één door het linkerteken te verwijderen en één door het rechterteken te verwijderen. Als een van hen een palindroom is, kunnen we een volledig stringpalindroom maken door het overeenkomstige teken te verwijderen. Als beide substrings geen palindroom zijn, is het niet mogelijk om van de volledige string een palindroom te maken onder bepaalde beperkingen.
Uitvoering:
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>
Uitvoer
Not Possible
Tijdcomplexiteit: O(N)
Ruimtecomplexiteit: O(1)
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