Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.
Note: For the purpose of this problem, we define empty string as valid palindrome.
Example 1:
Input: "A man, a plan, a canal: Panama"
Output: true
Example 2:
Input: "race a car"
Output: false
/**
* @param {string} s
* @return {boolean}
*/
let isPalindrome = function (s) {
const clean = s.toLowerCase().split(/[^a-z0-9]*/);
return clean.join("") === clean.reverse().join("");
};Remove non-alphanumeric characters then compare.
/**
* @param {string} s
* @return {boolean}
*/
let isPalindrome = function (s) {
const clean = s.replace(/[^a-zA-Z0-9]/g, "").toLowerCase();
for (let i = 0, j = clean.length - 1; i < j; i++, j--) {
if (clean[i] !== clean[j]) {
return false;
}
}
return true;
};Compare the char codes.
/**
* @param {string} s
* @return {boolean}
*/
let isPalindrome = function (s) {
for (let i = 0, j = s.length - 1; i < j; i++, j--) {
let left = s.charCodeAt(i);
while (
i < j &&
(left < 48 ||
(left > 57 && left < 65) ||
(left > 90 && left < 97) ||
left > 122)
) {
left = s.charCodeAt(++i);
}
if (i >= j) {
return true;
}
if (left >= 65 && left <= 90) {
left += 32;
}
let right = s.charCodeAt(j);
while (
i < j &&
(right < 48 ||
(right > 57 && right < 65) ||
(right > 90 && right < 97) ||
right > 122)
) {
right = s.charCodeAt(--j);
}
if (i >= j) {
return true;
}
if (right >= 65 && right <= 90) {
right += 32;
}
if (left !== right) {
return false;
}
}
return true;
};☆: .｡. o(≧▽≦)o .｡.:☆☆: .｡. o(≧▽≦)o .｡.:☆☆: .｡. o(≧▽≦)o .｡.:☆
☆: .｡. o(≧▽≦)o .｡.:☆☆: .｡. o(≧▽≦)o .｡.:☆