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
str = sys.stdin.readline().strip()
recorded = []
rep = set()
for s in str:
if s in recorded:
recorded.remove(s)
rep.add(s)
if s not in recorded and s not in rep:
recorded.append(s)
if recorded != []:
print(recorded[0])
else:
print(-1)
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