POJ 1007(无序度 排序) 解题报告

/*__________________________________________________________POJ 1007题_________________________________________________________________
DNA Sorting
Time Limit: 1000MS  Memory Limit: 10000K
Total Submissions: 45169  Accepted: 17618
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<string>
#include<stdlib.h>
using namespace std;

typedef struct DNAstring{
string str;
int unsortedness;
}DNAstring;

/*
#include<fstream>
fstream fin("input.txt",ios::in);
#define cin fin
//*/

void CountUnsortedness(struct DNAstring *m)
{
int i,j;
for(i=0;i<m->str.length();i++)
for(j=i+1;j<m->str.length();j++)
{
if(m->str[i]>m->str[j])
{
m->unsortedness++;
//	cout<<m->unsortedness;
}
}
}

int cmp(const void*a,const void*b)
{
return (*(DNAstring *)a).unsortedness - (*(DNAstring *)b).unsortedness;
}

int main()
{
int i;
int length,n;
cin>>length>>n;

struct DNAstring *inputStr=new struct DNAstring
;
for(i=0;i<n;i++)
{
cin>>inputStr[i].str;
inputStr[i].unsortedness=0;
//cout<<inputStr[i].str<<"  "<<inputStr[i].unsortedness<<endl;
CountUnsortedness(&inputStr[i]);
//cout<<inputStr[i].str<<"  "<<inputStr[i].unsortedness<<endl<<endl;
}

qsort(inputStr,n,sizeof(struct DNAstring),cmp);

for(i=0;i<n;i++)
cout<<inputStr[i].str<<endl;

return 0;
}
//总结：通过此题会用<stdlib.h>中的qsort()快排函数了