杰拉斯的博客

304 的标准解释是：Not Modified 客户端有缓冲的文档并发出了一个条件性的请求（一般是提供If-Modified-Since头表示客户只想比指定日期更新的文档）。服务器告诉客户，原来缓冲的文档还可以继续使用。

如果客户端在请求一个文件的时候，发现自己缓存的文件有 Last Modified ，那么在请求中会包含 If Modified Since ，这个时间就是缓存文件的 Last Modified 。因此，如果请求中包含 If Modified Since，就说明已经有缓存在客户端。只要判断这个时间和当前请求的文件的修改时间就可以确定是返回 304 还是 200 。对于静态文件，例如：CSS、图片，服务器会自动完成 Last Modified 和 If Modified Since 的比较，完成缓存或者更新。但是对于动态页面，就是动态产生的页面，往往没有包含 Last Modified 信息，这样浏览器、网关等都不会做缓存，也就是在每次请求的时候都完成一个 200 的请求。

因此，对于动态页面做缓存加速，首先要在 Response 的 HTTP Header 中增加 Last Modified 定义，其次根据 Request 中的 If Modified Since 和被请求内容的更新时间来返回 200 或者 304 。虽然在返回 304 的时候已经做了一次数据库查询，但是可以避免接下来更多的数据库查询，并且没有返回页面内容而只是一个 HTTP Header，从而大大的降低带宽的消耗，对于用户的感觉也是提高。

(阅读全文…)

这些CSS工具都是很适合网页设计题使用，已经为大家分好类别，请自行点击导航快速浏览：

• 网格和布局
• CSS 优化和样式生成
• CSS 菜单工具
• CSS 按钮
• CSS 圆角
• CSS 框架
• CSS 表格
• CSS Sprites | CSS精灵
• CSS 文本和字体
• CSS 表单

网格和布局，CSS 优化，CSS 菜单工具，CSS 按钮，CSS 圆角，CSS 框架，CSS Sprites，CSS 排版以及 CSS 表单。

(阅读全文…)

Crixalis's Equipment

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1350 Accepted Submission(s): 543

Description

Crixalis - Sand King used to be a giant scorpion(蝎子) in the deserts of Kalimdor. Though he's a guardian of Lich King now, he keeps the living habit of a scorpion like living underground and digging holes.

Someday Crixalis decides to move to another nice place and build a new house for himself (Actually it's just a new hole). As he collected a lot of equipment, he needs to dig a hole beside his new house to store them. This hole has a volume of V units, and Crixalis has N equipment, each of them needs Ai units of space. When dragging his equipment into the hole, Crixalis finds that he needs more space to ensure everything is placed well. Actually, the ith equipment needs Bi units of space during the moving. More precisely Crixalis can not move equipment into the hole unless there are Bi units of space left. After it moved in, the volume of the hole will decrease by Ai. Crixalis wonders if he can move all his equipment into the new hole and he turns to you for help.

Input

The first line contains an integer T, indicating the number of test cases. Then follows T cases, each one contains N + 1 lines. The first line contains 2 integers: V, volume of a hole and N, number of equipment respectively. The next N lines contain N pairs of integers: Ai and Bi.
0

Output

For each case output "Yes" if Crixalis can move all his equipment into the new hole or else output "No".

Sample Input

2

20 3
10 20
3 10
1 7

10 2
1 10
2 11

Sample Output

Yes
No

Source

HDU3177

(阅读全文…)

问题描述

MARQUEE 标记中存在 "behavior" 值为 "alternate" 时，MARQUEE 标记内的处于普通流中块元素的交替往复移动效果消失。

造成的影响

在 Chrome Safari 中 MARQUEE 标记失效。

受影响的浏览器

Chrome Safari

(阅读全文…)

A+B for Input-Output Practice (I)

Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 13098 Accepted Submission(s): 6187

Description

Your task is to Calculate a + b.
Too easy?! Of course! I specially designed the problem for acm beginners.
You must have found that some problems have the same titles with this one, yes, all these problems were designed for the same aim.

Input

The input will consist of a series of pairs of integers a and b, separated by a space, one pair of integers per line.

Output

For each pair of input integers a and b you should output the sum of a and b in one line, and with one line of output for each line in input.

Sample Input

1 5
10 20

Sample Output

6

30

(阅读全文…)