1_4_1 Packing Rectangles

USACO 1.4.1 Packing Rectangles
Packing Rectangles
IOI 95
The six basic layouts of four rectangles
Four rectangles are given. Find the smallest enclosing (new) rectangle into which these four may be fitted without overlapping. By smallest rectangle, we mean the one with the smallest area.
All four rectangles should have their sides parallel to the corresponding sides of the enclosing rectangle. Figure 1 shows six ways to fit four rectangles together. These six are the only possible basic layouts, since any other layout can be obtained from a basic layout by rotation or reflection. Rectangles may be rotated 90 degrees during packing.
There may exist several different enclosing rectangles fulfilling the requirements, all with the same area. Y ou must produce all such enclosing rectangles.
PROGRAM NAME: packrec
INPUT FORMA T
Four lines, each containing two positive space-separated integers that represent the lengths of a rectangle's two sides. Each side of a rectangle is at least 1 and at most 50.
SAMPLE INPUT (file packrec.in)
1 2
2 3
3 4
4 5
OUTPUT FORMA T
The output file contains one line more than the number of solutions. The first line contains a single integer: the minimum area of the enclosing rectangles. Each of the following lines contains one solution described by two numbers p and q with p<=q. These lines must be sorted in ascending order of p, and must all be different.
SAMPLE OUTPUT (file packrec.out)
40
4 10
5 8
Packing Rectangles
铺放矩形块
IOI 95
译by leontea
给定4个矩形块，找出一个最小的封闭矩形将这4个矩形块放入，但不得相互重叠。

所谓最小矩形指该矩形面积最小。

所有4个矩形块的边都与封闭矩形的边相平行，图1示出了铺放4个矩形块的6种方案。

这6种方案仅只是可能的基本铺放方案。

因为其它方案能由基本方案通过旋转和镜像反射得到。

可能存在满足条件且有着同样面积的各种不同的封闭矩形，你应该输出所有这些封闭矩形的边长。

PROGRAM NAME: packrec
INPUT FORMA T
共有4行。

每一行用两个正整数来表示一个给定的矩形块的两个边长。

矩形块的每条边的边长范围最小是1，最大是50。

SAMPLE INPUT (file packrec.in)
1 2
2 3
3 4
4 5
OUTPUT FORMA T
总行数为解的总数加1。

第一行是一个整数，代表封闭矩形的最小面积（子任务A）。

接下来的每一行都表示一个解，由数P和数Q来表示，并且P≤Q（子任务B）。

这些行必须根据P的大小按升序排列，P小的行在前，大的在后。

且所有行都应是不同的。

SAMPLE OUTPUT (file packrec.out)
40
4 10
5 8。