POJ 1007 DNA Sorting

DNA Sorting

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 59510		Accepted: 23481

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

//

#include <iostream>

#include <cstdio>

#include <string>

#include <cstring>

#include <algorithm>

using namespace std;

char ss[110][100];

char back[110][100];

struct Rev

{

int i; //下标

int rev;

};

int comp1(const void *a,const void *b)

{

return (*(Rev *)a).rev > (*(Rev *)b).rev ? 1 : -1;

}

int m,n;

int cnt;

void mergesort(int i,int j,char *str,char *str1)

{

if(j-i>1)

{

int m=(i+j)/2;

mergesort(i,m,str,str1);

mergesort(m,j,str,str1);

int p=i,q=m; int l=i;

while(p<m||q<j)

{

if((p<m&&str[p]<=str[q])||q>=j) str1[l++]=str[p++];

else {str1[l++]=str[q++]; cnt+=m-p;}

}

for(int k=i;k<j;k++)

str[k]=str1[k];

}

}

int main() {

while(scanf("%d%d",&n,&m)==2)

{

Rev r[110];

for(int i=0;i<m;i++)

{

scanf("%s",ss[i]);

memcpy(back[i],ss[i],sizeof(ss[i]));

char str1[50];

cnt=0;

mergesort(0,n,ss[i],str1);

r[i].rev=cnt;

r[i].i=i;

}

qsort(r,m,sizeof(r[0]),comp1);

for(int i=0;i<m;i++)

cout<<back[r[i].i]<<endl;

}

return 0;

}