class Solution:
    def maxNumOfSubstrings(self, s: str) -> List[str]:
      chars = {}
      for i,c in enumerate(s):
        if c not in chars:
          chars[c] = [i,i+1]
        else:
          chars[c][1] = i+1
      #扩展字母的范围
      lrange = []
      for start, end in chars.values():
        i = start + 1
        max_end = end
        while i < max_end:  # 不断往后拓展区间，以满足条件 2
          if chars[s[i]][0] < start:  # 不往前拓展
            break
          max_end = max(max_end, chars[s[i]][1])
          i += 1
        else:
          lrange.append([start, max_end])

      lrange.sort()
      prer = [0, 0]
      res = []
      for r in lrange:
        left,right  = r[0], r[1]
        if right <= prer[1] and len(res):
          res.pop(-1)
        res.append(s[left:right])
        prer = [left, right]
      return res