摘要：Problem: Given an array of integers, return indices of the two numbers such that they add up to a specific target. You may assume that each input woul 阅读全文

摘要：Problem: Given a string, find the first non-repeating character in it and return it's index. If it doesn't exist, return -1. Example: 本题的第一想法是开一个字母表计数 阅读全文