Reverse Vowels of a String

Two Pointer Approach

• Convert the string into a character array for easy manipulation.
• Initialize two pointers: one at the start and one at the end of the array.
• Use a Set to store all vowels (both uppercase and lowercase).
• Move the pointers inward while skipping non-vowel characters.
• When both pointers are at vowels, swap the characters.
• Continue this process until the two pointers meet.
• Finally, join the array back into a string and return it.

var reverseVowels = function (s) {
  const vowels = new Set(["a", "e", "i", "o", "u", "A", "E", "I", "O", "U"]);
  const chars = s.split("");
  let start = 0;
  let end = s.length - 1;

  while (start < end) {
    while (start < end && !vowels.has(chars[start])) start++;
    while (start < end && !vowels.has(chars[end])) end--;

    [chars[start], chars[end]] = [chars[end], chars[start]];
    start++;
    end--;
  }

  return chars.join("");
};