摘要：
题目描述 Given a string, find the length of the longest substring without repeating characters. For example, the longest substring without repeating lette 阅读全文
摘要：
Reverse digits of an integer. Example1: x = 123, return 321 Example2: x = 123, return 321 Have you thought about this? Here are some good questions to 阅读全文
摘要：
``` package cn.lbd.Collection; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Set; /**统计单词出现的次数 * this is a cat and this is a mice and where is the food... 阅读全文