Valid Palindrome II

Write a function that takes a string as input and checks whether it can be a valid palindrome by removing at most one character from it.

Write a function that takes a string as input and checks whether it can be a valid palindrome by removing at most one character from it.

Constraints

• 1 ≤ string.length ≤ 10³
• The string only consists of English letters.

Examples

Example 1

Input: "ABCEBA" Output: TRUE

Example 2

Input: "RACEACAT" Output: FALSE

Example 3

Input: "DEEAD" Output: TRUE

Solution To solve this, I'll reuse Previously generated IsPalindrome function. We'll add a condition before rejecting it check for substring start+1 and end-1 if any of them is palindrome our string is palindrome

function isPalindrome(str) {
    let start = 0;
    let end = str.length - 1;
    while (start <= end) {
        if (str[start] !== str[end]) {
            return false;
        }
        start++;
        end--;
    }
    return true;
}

function validPalindromII(str) {
    let start = 0;
    let end = str.length - 1;
    while (start <= end) {
        if (str[start] !== str[end]) {
            return (
                isPalindrome(str.slice(start, end)) ||       // drop char at `end`
                isPalindrome(str.slice(start + 1, end + 1))  // drop char at `start`
            );
        }
        start++;
        end--;
    }
    return true;
}

console.log(validPalindromII('DEEAD'));     // true
console.log(validPalindromII('ABBAC'));     // true
console.log(validPalindromII('ABCEBA'));    // true
console.log(validPalindromII('RACEACAT'));  // false