POJ1007-DNA Sorting-ACM

DNA Sorting

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 83442		Accepted: 33584

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

重点，归并排序求逆序数

 #include <stdio.h>
 #include <malloc.h>
 #include <string.h>
 #define MAXN 256
 char a[MAXN];
 char c[MAXN];
 int cnt=;
 void MergeSort(int l, int r){
     int mid, i, j, tmp;
     if( r > l+ ){
         mid = (l+r)/;
         MergeSort(l, mid);
         MergeSort(mid, r);
         tmp = l;
         for( i=l, j=mid; i < mid && j < r; ){
             if( a[i] > a[j] ){
                 c[tmp++] = a[j++];
                 cnt += mid-i; //
             }
             else c[tmp++] = a[i++];
         }
         if( j < r ) for( ; j < r; ++j ) c[tmp++] = a[j];
         else for( ; i < mid; ++i ) c[tmp++] = a[i];
         for ( i=l; i < r; ++i ) a[i] = c[i];
     }
 }
 int main(void){
     int n,m;
     scanf("%d%d",&n,&m);
     char ** strs = (char **)malloc(m*sizeof(char*));
     int * cnts = (int *)malloc(m*sizeof(int));
     int i;
     for(i = ;i<m;i++){
         strs[i] = (char *)malloc((n+)*sizeof(char));
         scanf("%s",strs[i]);
         //printf("%s\n",strs[i]);
         cnt = ;
         strcpy(a,strs[i]);
         //printf("%s\n",a);
         MergeSort(,n);
         //printf("%d\n",cnt);
         cnts[i] = cnt;
     }

     for(i = ;i<m-;i++){
         int j,p=i;
         for(j = i+;j<m;j++){
             if(cnts[p]>cnts[j]){
                 p = j;
             }
         }
         if(p!=i){
             int tmp = cnts[p];
             cnts[p] = cnts[i];
             cnts[i] = tmp;
             char * str = strs[p];
             strs[p] = strs[i];
             strs[i] = str;
         }
     }
     for(i = ;i<m;i++){
         printf("%s\n",strs[i]);
         free(strs[i]);
     }
     free(strs);
     free(cnts);
     return ;
 }