fd

Author: liwentian

.DS_Store

@@ -3,8 +3,12 @@
 import android.app.Activity;
 import android.os.Bundle;
 
+import java.util.concurrent.DelayQueue;
+
 public class MainActivity extends Activity {
 
+    private DelayQueue
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

ToDo.md

@@ -0,0 +1,56 @@
+package com.inuker.solution.system;
+
+/**
+ * Created by liwentian on 2017/10/17.
+ */
+
+public class DesignTinyURL {
+
+    /**
+     * 这题和#535. Encode and Decode TinyURL类似，不过这题更偏向于系统设计
+     *
+     * 1. How many unique identifiers possible? Will you run out of unique URLs?
+     * 如果按6个字符计算，一共有62**6种可能，大概三百多亿，越到后面碰撞越来越多，可以通过增加字符数来解决
+     *
+     * 2. Should the identifier be increment or not? Which is easier to design? Pros and cons?
+     * 不能，那样容易被破解，比如爬虫直接按ID递增的顺序一个个抓即可。
+     *
+     * 3. Mapping an identifier to an URL and its reversal - Does this problem ring a bell to you?
+     *
+     * 4. How do you store the URLs? Does a simple flat file database work?
+     * 采用分布式，负载均衡随机分发到一台机器，KV数据库，以短网址为key，长网址为value
+     *
+     * 5. What is the bottleneck of the system? Is it read-heavy or write-heavy?
+     * 读显然比写多，比如用户在微博分享了一个资源，以短链接的形式。很多用户访问这个链接，则读远大于写。
+     *
+     *
+     * 6. Estimate the maximum number of URLs a single machine can store.
+     *
+     * 7. Estimate the maximum number of queries per second (QPS) for decoding a shortened URL in a single machine.
+     *
+     * 8. How would you scale the service? For example, a viral link which is shared in social media could result in a peak QPS at a moment's notice.
+     *
+     * 9. How could you handle redundancy? i,e, if a server is down, how could you ensure the service is still operational?
+     * 一致性哈希，虚拟节点
+     *
+     *
+     * 10. Keep URLs forever or prune, pros/cons? How we do pruning?
+     *
+     * 11. What API would you provide to a third-party developer?
+     * encode, decode
+     *
+     * 12. If you can enable caching, what would you cache and what's the expiry time?
+     * KV db, key为short url，value为long url
+     *
+     *
+     * 13, 如何防攻击？假如有人大量发相同的url耗光
+     * 限制IP；一台KV服务器做缓存，key为long url，value为短url，如果缓存中有直接返回，cache是LRU的
+     *
+     *
+     */
+
+
+    /**
+     * 可参考https://segmentfault.com/a/1190000006140476
+     */
+}

app/src/main/java/com/inuker/leetcode/MainActivity.java

@@ -0,0 +1,11 @@
+package com.inuker.solution.system;
+
+/**
+ * Created by liwentian on 2017/10/17.
+ */
+
+public class Info {
+    /**
+     * 可参考https://www.gitbook.com/@soulmachine
+     */
+}