find-the-longest-substring-containing-vowels-in-even-counts.ts

/**
 * @param {string} s
 * @return {number}
 */
export const findTheLongestSubstring = function (s: string) {
  const n = s.length
  const pos = new Array(1 << 5).fill(-1)
  let ans = 0; let status = 0
  pos[0] = 0
  for (let i = 0; i < n; ++i) {
    const ch = s.charAt(i)
    if (ch === 'a') {
      status ^= 1 << 0
    } else if (ch === 'e') {
      status ^= 1 << 1
    } else if (ch === 'i') {
      status ^= 1 << 2
    } else if (ch === 'o') {
      status ^= 1 << 3
    } else if (ch === 'u') {
      status ^= 1 << 4
    }
    if (~pos[status]) {
      ans = Math.max(ans, i + 1 - pos[status])
    } else {
      pos[status] = i + 1
    }
  }
  return ans
}