HDU-1074 Doing Homework( 状压DP )

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=1074

[align=left]Problem Description[/align]
Ignatius has just come back school from the 30th ACM/ICPC. Now he has a lot of homework to do. Every teacher gives him a deadline of handing in the homework. If Ignatius hands in the homework after the deadline, the teacher will reduce his score of the final test, 1 day for 1 point. And as you know, doing homework always takes a long time. So Ignatius wants you to help him to arrange the order of doing homework to minimize the reduced score.

[align=left]Input[/align]
The
input contains several test cases. The first line of the input is a
single integer T which is the number of test cases. T test cases follow.
Each
test case start with a positive integer N(1<=N<=15) which
indicate the number of homework. Then N lines follow. Each line contains
a string S(the subject's name, each string will at most has 100
characters) and two integers D(the deadline of the subject), C(how many
days will it take Ignatius to finish this subject's homework).

Note: All the subject names are given in the alphabet increasing order. So you may process the problem much easier.

[align=left]Output[/align]
For
each test case, you should output the smallest total reduced score,
then give out the order of the subjects, one subject in a line. If there
are more than one orders, you should output the alphabet smallest one.

[align=left]Sample Input[/align]

2

3

Computer 3 3

English 20 1
Math 3 2
3
Computer 3 3

English 6 3

Math 6 3

[align=left]Sample Output[/align]
2

Computer

Math
English

3

Computer

English

Math

做这题时还没学状压DP，参照网上的博文学习了一下。
状态压缩 由于数据量不大，所以可以用二进制表示每一个状态。给出状态i，对于每一个作业j，i&( 1 << j )表示第j个作业在状态i中是否完成，于是又dp[i] = max( dp[i - ( 1 << j )] + re[j] ),re[j]表示通过作业j由i的前一个状态转到状态i增加的损失。
输出 由于作业名已排序，所以更新状态时由n-1到0即可保证字典序最小。