Problem-3_Check_for_Palindrome.js

// Problem-3_Check_for_Palindrome with Solution, Explanation, Verification, and Execution:

// To check for palindrome, we can implement the Solution like below:
// -------------------------------------------------------------------

function isPalindrome(word) {
    let left = 0;
    let right = word.length - 1;
    while (left < right) {
        if (word[left].toLowerCase() !== word[right].toLowerCase()) {
            return false;
        }
        left++;
        right--;
    }
    return true;
}

// Explanation: 
// ---------------
// This function uses two pointers: one starting at the beginning (left) and one at the end (right) of the string. It enters a while loop that continues as long as the pointers have not crossed each other. In each iteration, it compares the characters at the pointers (converted to lowercase for case-insensitivity); if they differ, it returns false. Otherwise, it moves the left pointer forward and the right backward. If the loop completes without mismatches, it returns true. This two-pointer technique efficiently checks symmetry without creating a reversed copy.

// Verification:
// ----------------
// Example-1:
// function isPalindrome(madam) {
//     let left = 0;
//     let right = madam.length - 1;
//     while (left < right) {
//         if (madam[left].toLowerCase() !== madam[right].toLowerCase()) {
//             return false;
//         }
//         left++;
//         right--;
//     }
//     return true;
// }
// console.log(isPalindrome("madam"));

// Example-2:
// function isPalindrome(hello) {
//     let left = 0;
//     let right = hello.length - 1;
//     while (left < right) {
//         if (hello[left].toLowerCase() !== hello[right].toLowerCase()) {
//             return false;
//         }
//         left++;
//         right--;
//     }
//     return true;
// }
// console.log(isPalindrome("hello"));

// Execution of the above code block in IDE environment with node.js installed:
// ----------------------------------------------------------------------
// Input (In the directory in IDE environment with node.js installed): 'node Problem-3_Check_for_Palindrome.js'
// Output (In the directory in IDE environment with node.js installed): '3'