by jiangshan @jiangshanmeta
Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1. (Inspired by leetcode 387)
by jiangshan @jiangshanmeta
Given a string s, find the first non-repeating character in it and return its index. If it does not exist, return -1. (Inspired by leetcode 387)