UVa 10602 Editor Nottoobad (等价转换思想)

10602 - Editor Nottoobad

Time limit: 3.000 seconds

http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=113&page=show_problem&problem=1543

Company Macrohard has released it’s new version of editor Nottoobad, which can understand a few voice commands. Unfortunately, there are only two voice commands that it can understand – “repeat the last word”, “delete the last symbol”. However, when one
uses “repeat the last word” the editor inserts a blank that separates the words. But the company claims that it is possible to type much faster – simply by less number of presses. For example, such a phrase like “this thin thing” requires only 6 presses of
the keyboard.

Action	Number of presses	Content of the document
Press "this"	4	This
Say “repeat the last word”	0	this this
Say “delete the last symbol”	0	this thi
Press "n"	1	this thin
Say “repeat the last word”	0	this thin thin
Press "g"	1	this thin thing

In order to increase the popularity of it’s product the company decided to organize a contest where the winner will be a person who types a given number of words with minimum number of presses. Moreover, the first word must be typed first, and all the others
can be typed in arbitrary order. So, if words “apple”, “plum” and “apricote” must be typed, the word “apple” must be typed first, and the words “plum” and “apricote” can be switched. And the most important for you – you are going to take part in the contest
and you have a good friend in the company, who told you the word which will be used in the contest. You want be a winner J, so you have to write a program which finds the order of the words, where the number of presses will be minimum.

Input

The first line of the input contains the T (1≤T≤15) the number of test cases. Then T test cases follow. The first line of each test contains a number N (1≤N≤100) – the number of words that must be pressed. Next N lines contain words – sequences of small
Latin letters, not longer than 100 symbols. Remember that the first word must be pressed first!

Output

The first line of the output contains number X - the minimum number of presses, which one has to do in order to type all the words using editor
Nottoobad. Next N lines contain the words in that minimum order. If there are several solutions, you can output one of them.

Sample Input	Sample Output
3 3 this thin thing 4 popcorn apple apricote plum 2 hello hello	6 this thin thing 21 popcorn plum apricote apple 5 hello hello

观察到：无论选择哪个单词开始，在贪心后的结果，都是一样的。

证明：首先最少的press次数肯定是在输出排序后的字符串后得到的。基于这个顺序，我们有：对于两个首字母不同的单词，二者在press时都要完整地敲出来，press次数必为二者长度之和；而对于两个首字母相同的单词，press次数必为（在贪心的思想下）不相同的部分之和。所以二者的顺序是无关的。

完整代码：

/*0.009s*/

#include<cstdio>
#include<cstring>
#include<cstdlib>
#define sf scanf
#define pf printf

char word[105][105];

int cmp(const void* a, const void* b)
{
	return strcmp((char*)a, (char*)b);
}

int main()
{
	int t, n, sum, i, j;
	sf("%d", &t);
	while (t--)
	{
		sf("%d\n", &n);
		for (i = 0; i < n; ++i)
			gets(word[i]);
		qsort(word, n, sizeof(word[0]), cmp);
		sum = strlen(word[0]);
		for (i = 1; i < n; ++i)
		{
			for (j = 0; word[i][j] && word[i - 1][j] && word[i][j] == word[i - 1][j]; ++j)
				;
			sum += strlen(word[i]) - j;
		}
		pf("%d\n", sum);
		for (i = 0; i < n; ++i)
			puts(word[i]);
	}
	return 0;
}