Palindrome Check

Write a function that takes in a non-empty string and that returns a boolean representing whether the string is a palindrome.

A palindrome is defined as a string that's written the same forward and backward. Note that single-character strings are palindromes.

Sample Input

string = "abcdcba"

string = "abcdcba"

Sample Output

true // it's written the same forward and backward

true // it's written the same forward and backward

Hints

Hint 1

Start by building the input string in reverse order and comparing this newly built string to the input string. Can you do this without using string concatenations?

Hint 2

Can you optimize your algorithm by using recursion? What are the implications of recursion on an algorithm's space-time complexity analysis?

Hint 3

Go back to an iterative solution and try using pointers to solve this problem: start with a pointer at the first index of the string and a pointer at the final index of the string. What can you do from there?

Optimal Space & Time Complexity

O(n) time | O(1) space - where n is the length of the input string

function isPalindrome(string) {
  if (string.length === 1) return true;
	if (string.length === 2) {
		if (string[0] === string[1]) {
			return true
		} else return false
	}
	string.charAt[string.length]
	if (string[0] === string[string.length - 1]) {
		let sliced = string.slice(1, string.length - 1)
		return isPalindrome(sliced);
	}
	return false
}

function isPalindrome(string) {
  if (string.length === 1) return true;
	if (string.length === 2) {
		if (string[0] === string[1]) {
			return true
		} else return false
	}
	string.charAt[string.length]
	if (string[0] === string[string.length - 1]) {
		let sliced = string.slice(1, string.length - 1)
		return isPalindrome(sliced);
	}
	return false
}

function isPalindrome(string) {
	let reversedString = '';
	for (let i = string.length - 1; i >= 0; i--) {
		reversedString += string[i];
	}
	return string === reversedString;
}

function isPalindrome(string) {
	let reversedString = '';
	for (let i = string.length - 1; i >= 0; i--) {
		reversedString += string[i];
	}
	return string === reversedString;
}

🐉