安装 FFmpeg，直奔官网。

将 gif 转为 mp4

Twitter 宣布支持 gif 图片，它其实是将 gif 转为 mp4 再通过 <video> 标签展示的，这样的好处有：

• 不必等全部资源加载完成再进行展示
• gif 文件转为 mp4 格式后，文件大小差别相当大，gif 大小为 2MB，转为 mp4 大小为 260KB
• 可以对动画进行播放、暂停、拖曳控制

本文包含的 ArrayList 用法可在上篇文章找到，先上代码：

先来一段代码：

What is FormData

MDN

XMLHttpRequest Level 2 adds support for the new FormData interface. FormData objects provide a way to easily construct a set of key/value pairs representing form fields and their values, which can then be easily sent using the XMLHttpRequest send() method.

按照 Android Studio 内置的例子做了个 actionbar 的 Demo，现在写下来做笔记，IDE 为 Android Studio v1.2。 完成的截图如下：

Transfer decimal number to its corresponding binary number in a quick way.

来一个直观的图解释插入排序（图来自 Insertion Sort）：

今天下载了个字幕文件，不过里面的分行太多，明明只是简单的一个不长句子，硬是被分成两行，于是我决定把这些分行全部去掉，字幕文件部分片段如下：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22

2
00:01:15,452 --> 00:01:18,843
This is Zero One Alpha. We
have secured the Falcon.
3
00:01:18,868 --> 00:01:21,476
I say again,We have
secured the Falcon.

4
00:01:22,952 --> 00:01:26,452
I will count from one to ten. Within
that you'll tell me what I wanna know.

5
00:01:27,052 --> 00:01:28,752
Otherwise,

6
00:01:29,177 --> 00:01:32,152
<span style="color: #00ff00;">the number ten is
the last thing you'll hear.

What exactly is the Tower of Hanoi, here is the explanation from Tower of Hanoi:

The Tower of Hanoi is a mathematical game or puzzle. It consists of three rods, and a number of disks of different sizes which can slide onto any rod. The puzzle starts with the disks in a neat stack in ascending order of size on one rod, the smallest at the top, thus making a conical shape.

The objective of the puzzle is to move the entire stack to another rod, obeying the following simple rules:

1. Only one disk can be moved at a time.
2. Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack i.e. a disk can only be moved if it is the uppermost disk on a stack.
3. No disk may be placed on top of a smaller disk.

来自维基百科的定义：

斐波那契數的特點是每一個數都是前二個數的和。頭二項是0和1，此數列的前幾項如下： 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987…