POJ 1007 DNA Sorting（sort函数的使用）

Description

One measure of ``unsortedness'' in a sequence is the number of pairs of entries that are out of order with respect to each other. For instance, in the letter sequence ``DAABEC'', this measure is 5, since D is greater than four letters to its right and E is greater than one letter to its right. This measure is called the number of inversions in the sequence. The sequence ``AACEDGG'' has only one inversion (E and D)---it is nearly sorted---while the sequence ``ZWQM'' has 6 inversions (it is as unsorted as can be---exactly the reverse of sorted).

You are responsible for cataloguing a sequence of DNA strings
(sequences containing only the four letters A, C, G, and T). However,
you want to catalog them, not in alphabetical order, but rather in order
of ``sortedness'', from ``most sorted'' to ``least sorted''. All the
strings are of the same length.

Input

The
first line contains two integers: a positive integer n (0 < n <=
50) giving the length of the strings; and a positive integer m (0 < m
<= 100) giving the number of strings. These are followed by m lines,
each containing a string of length n.

Output

Output
the list of input strings, arranged from ``most sorted'' to ``least
sorted''. Since two strings can be equally sorted, then output them
according to the orginal order.

Sample Input

10 6
AACATGAAGG
TTTTGGCCAA
TTTGGCCAAA
GATCAGATTT
CCCGGGGGGA
ATCGATGCAT

Sample Output

CCCGGGGGGA
AACATGAAGG
GATCAGATTT
ATCGATGCAT
TTTTGGCCAA
TTTGGCCAAA

 /*
 问题 输入每个字符串的长度n和字符串的个数，计算并将这些字符串的按照它的逆序数排序输出
 解题思路 将一个字符串和它的逆序数存入一个结构体数组中，使用sort按照逆序数排序输出即可。
 */
 #include<string>
 #include<cstring>
 #include<iostream>
 #include<algorithm>
 using namespace std;

 struct Dstr{
     string str;
     int cou;
 }Dstrs[];
 int unsortnum(char *str);

 bool cmp(struct Dstr a,struct Dstr b){
     return a.cou<b.cou;
 }

 int main()
 {
     int i,n,m;
     char temp[];
     while(scanf("%d%d",&n,&m) != EOF){
         for(i=;i<m;i++){
             scanf("%s",&temp);
             Dstrs[i].str=temp;
             Dstrs[i].cou=unsortnum(temp);
         }

         sort(Dstrs,Dstrs+m,cmp);

         for(i=;i<m;i++){
             printf(Dstrs[i].str.c_str());
             printf("\n");
         }
     }
     return ;
 } 

 int unsortnum(char *str){
     int len=strlen(str),i,j,un=;
     for(i=;i<len-;i++){
         for(j=i+;j<len;j++){
             if(str[i] > str[j])    un++;
         }
     }
     //printf("%s %d\n",str,un);
     return un;
 }