Given a string str, the task is to find whether the string is a palindrome or not in Java without using library methods.
Examples:
Input: str = “abba”
Output: YesInput: str = “geeks”
Output: No
Approach: Take two pointers i pointing to the start of the string and j pointing to the end of the string. Keep incrementing i and decrementing j while i < j and at every step check whether the characters at these pointers are same or not. If not then the string is not a palindrome else it is.
Below is the implementation of the above approach:
Java
// Java implementation of the approachpublic class GFG { // Function that returns true if // str is a palindrome static boolean isPalindrome(String str) { // Pointers pointing to the beginning // and the end of the string int i = 0, j = str.length() - 1; // While there are characters to compare while (i < j) { // If there is a mismatch if (str.charAt(i) != str.charAt(j)) return false; // Increment first pointer and // decrement the other i++; j--; } // Given string is a palindrome return true; } // Driver code public static void main(String[] args) { String str = "geeks"; if (isPalindrome(str)) System.out.print("Yes"); else System.out.print("No"); }} |
No
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