1371-find-the-longest-substring-containing-vowels-in-even-counts.js

/**
 * @param {string} s
 * @return {number}
 */
var findTheLongestSubstring = function(s) {
    const hash = {0: -1};
    const vowels = 'aeiou';
    const vowelsSet = new Set(vowels);
    const n = s.length;
    const key = (ch) => {
        const idx = vowels.indexOf(ch);
        return idx === -1 ? 0 : 1 << idx;
    }
    let state = 0;
    let res = 0;
    for(let i = 0; i < n; i++) {
        const ch = s[i]
        let tmp = state;
        if(vowelsSet.has(ch)) {
            tmp ^= key(ch);
        }
        if(hash[tmp] === undefined) {
            hash[tmp] = i;
        }else {
            res = Math.max(res, i - hash[tmp]);
        }

        state = tmp
    }

    return res
};

// another

/**
 * @param {string} s
 * @return {number}
 */
const findTheLongestSubstring = function(s) {
  const n = s.length
  let res = 0, mask = 0
  const map = new Map([[0, -1]])
  
  for(let i = 0; i < n; i++) {
    const ch = s[i]
    const idx = 'aeiou'.indexOf(ch)
    if(idx !== -1) {
      mask ^= (1 << idx)
    }
    if(map.has(mask)) {
      res = Math.max(res, i - map.get(mask))
    } else {
      map.set(mask, i)
    }
  }
  
  return res
};

// another

/**
 * @param {string} s
 * @return {number}
 */
const findTheLongestSubstring = function(s) {
  const n = s.length
  let res = 0, mask = 0
  const map = new Map([[0, -1]])
  
  for(let i = 0; i < n; i++) {
    const ch = s[i]
    const idx = 'aeiou'.indexOf(ch)
    if(idx !== -1) {
      mask ^= (1 << idx)
      if(map.has(mask)) {
        res = Math.max(res, i - map.get(mask))
      } else {
        map.set(mask, i)
      }
    } else {
      res = Math.max(res, i - map.get(mask))
    }
  }
  
  return res
};

// another

/**
 * @param {string} s
 * @return {number}
 */
const findTheLongestSubstring = function(s) {
  const n = s.length
  const ch2num = ch => {
    const idx = 'aeiou'.indexOf(ch)
    return idx === -1 ? 0 : (1 << idx)
  }
  let res = 0
  let mask = 0
  const hash = new Map([[0, -1]])
  for (let i = 0; i < n; i++) {
    mask ^= ch2num(s[i])
    const first = hash.has(mask) ? hash.get(mask) : i
    if (!hash.has(mask)) hash.set(mask, i)
    res = Math.max(res, i - first)
  }

  return res
};

// another

/**
 * @param {string} s
 * @return {number}
 */
var findTheLongestSubstring = function (s, V = 'aeiou', max = 0) {
  let encode = (c) => {
    let i = V.indexOf(c)
    return i == -1 ? 0 : 1 << i
  }
  let N = s.length
  let A = Array(N + 1).fill(0)
  let seen = new Map([[0, 0]])
  for (let i = 1; i <= N; ++i) {
    A[i] = A[i - 1] ^ encode(s[i - 1])
    let first = seen.has(A[i]) ? seen.get(A[i]) : i
    if (first == i) seen.set(A[i], i) // first seen A[i] index
    max = Math.max(max, i - first) // max of i-th index minus first seen A[i] index
  }
  return max
}

// another

/**
 * @param {string} s
 * @return {number}
 */
const findTheLongestSubstring = function(s) {
  const n = s.length
  const ch2num = ch => {
    const idx = 'aeiou'.indexOf(ch)
    return idx === -1 ? 0 : (1 << idx)
  }
  let res = 0
  let mask = 0
  const hash = new Map([[0, 0]])
  for (let i = 1; i <= n; i++) {
    mask ^= ch2num(s[i - 1])
    const first = hash.has(mask) ? hash.get(mask) : i
    if (!hash.has(mask)) hash.set(mask, i)
    res = Math.max(res, i - first)
  }

  return res
};

// another

/**
 * @param {string} s
 * @return {number}
 */
const findTheLongestSubstring = function (s) {
  let mask = 0
  const n = s.length,
    { max } = Math,
    map = new Map(),
    a = 'a'.charCodeAt(0),
    set = new Set(['a', 'e', 'i', 'o', 'u'])
  map.set(0, -1)
  let res = 0
  for (let i = 0; i < n; i++) {
    const ch = s[i]
    if (set.has(ch)) {
      const idx = ch.charCodeAt(0) - a
      mask ^= 1 << idx
      if (mask === 0) res = max(res, i + 1)
      else if (map.has(mask)) {
        res = max(res, i - map.get(mask))
      } else {
        map.set(mask, i)
      }
    } else {
        if(map.has(mask)) {
            // console.log(i, map.get(mask))
            res = max(res, i - map.get(mask))
        }
    }
  }

  return res
}