题解 | 找出字符串中第一个只出现一次的字符

import sys
from collections import Counter

raw_input = []
for i,line in enumerate(sys.stdin):
    raw_input.append(line.strip())
    if i == 1:
        break

input_str = raw_input[0]
res = -1
counts = Counter([c for c in input_str])
for c in input_str:
    if counts[c] == 1:
        res = c
        break
print(res)