function palindromeIndex1(s: string): number {
    // function check string [s] is palidrome
    const isPalindrome = (s: string): boolean => {
        for (let i = 0; i < Math.floor(s.length / 2); i++) {
            let ri = s.length - i - 1
            if (s[i] != s[ri]) return false
        }
        return true
    }

    // 1. check [s] isn't palindrome already
    if (!isPalindrome(s)) {
        // 2. loop [s]...
        for (let i = 0; i < s.length; i++)
            // 3. remove each character by [i], check remain [s] is palindrome
            if (isPalindrome(s.slice(0, i) + s.slice(i + 1)))
                // 4. found palindrome, return [i]
                return i
    }

    // 4. [s] alreay palidome, return -1
    return -1;
}

function palindromeIndex(s: string): number {
    // function check string [s] is palidrome
    const isPalindrome = (start: number, end: number): boolean => {
        while (start < end) {
            if (s[start] != s[end]) return false;
            start++;
            end--;
        }
        return true;
    }

    /**
     * solution 1 works fine but it seems to be suboptimal.
     * new idea is define 2 index at start and end of [s], reduce to middle.
     * only check 2 case when non palindrome found
     * + case1: start removed
     * + case2: end removed
     * orelse non of [s] can be palindrome, return -1
     */

    // 1. define [start] and [end]
    let start = 0
    let end = s.length - 1

    // 2. loop ... recude [start] and [end] to middle
    while (start < end) {
        // 3. if [s] at [start] and [end] is not equal, mean not palidrome at [start] to [end]
        if (s[start] != s[end]) {
            // 4.1 try remove [start], check palidrome ... return if found
            if (isPalindrome(start + 1, end)) return start
            // 4.2 try remove [end], check palidrome ... return if found
            if (isPalindrome(start, end - 1)) return end
        }
        start++
        end--
    }

    // [start] and [end] go throuth [s] but palidrome not found, return -1
    return -1;
}