leetcode学习笔记(第一个唯一字符)

class Solution:
    def firstUniqChar(self, s: str) -> int:
        amap = {}
        alist = list(s)
        for i in alist:
            if i in amap:
                amap[i] += 1
            else:
                amap[i] = 1
        for i in amap:
            if amap[i] == 1:
                return alist.index(i)
        return -1

class Solution:
    def firstUniqChar(self, s: str) -> int:
        frequency = collections.Counter(s)
        for i, ch in enumerate(s):
            if frequency[ch] == 1:
                return i
        return -1