这题思路跑偏了, 最开始想的是建一棵树来做, 写了一一堆代码, 还只能通过部分 case

动态规划解很优雅, 这个题很舒服

/**
 * @param {string[]} words
 * @return {number}
 */
const longestStrChain = function (words) {
  const f = [];
  let ans = 0;
  words.sort((a, b) => {
    return a.length - b.length;
  })
  for (w of words) {
    l = w.length
    for (let i = 1; i <= l; ++i) {
      f[w.slice(0, i - 1) + w.slice(i)] = f[w.slice(0, i - 1) + w.slice(i)] || 0
      f[w] = f[w] || 0
      f[w] = Math.max(f[w], f[w.slice(0, i - 1) + w.slice(i)] + 1)
      ans = Math.max(ans, f[w])
    }
  }
  return ans
};