题解 | #找出字符串中第一个只出现一次的字符#
找出字符串中第一个只出现一次的字符
https://www.nowcoder.com/practice/e896d0f82f1246a3aa7b232ce38029d4
import sys
s = input()
dic = {}
for c in s:
dic[c] = dic.get(c, 0)+1
if 1 in dic.values():
for k in dic.keys():
if dic[k] == 1:
print(k)
break
else:
print(-1)