Sliding window and two pointers in JavaScript

Sliding window

Use when you need a contiguous subarray or substring.

Problems to practice

• Longest substring without repeating characters
• Maximum sum subarray of size K
• Minimum window substring
• Permutation in a string

Two pointers

Used for sorted arrays and palindrome checks.

Example: valid palindrome

function isPalindrome(s) {
  let left = 0;
  let right = s.length - 1;

  while (left < right) {
    if (s[left] !== s[right]) return false;
    left++;
    right--;
  }

  return true;
}