POJ 1007

DNA Sorting
Time Limit: 1000MS
 
Memory Limit: 10000K
Total Submissions: 88227
 
Accepted: 35442
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


import java.util.Scanner;

public class Poj1007 {

	private static DNA[] ret;

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int m = sc.nextInt();

		ret = new DNA[m];

		for (int i = 0; i < m; i++) {
			DNA dna = new DNA();
			dna.value = sc.next();
			dna.sortNum = calSortNum(dna.value);
			// ret[i] = dna;
			addToArray(dna);
		}

		for (int i = 0; i < m; i++) {
			System.out.println(ret[i].value);
		}
	}

	//      
	private static int calSortNum(String str) {

		if (str.length() == 1) {
			return 0;
		}

		int sortF = 0;
		char c = str.charAt(0);
		for (int i = 1; i < str.length(); i++) {
			if (c > str.charAt(i)) {
				sortF++;
			}
		}
		return sortF + calSortNum(str.substring(1));
	}

	//    
	private static void addToArray(DNA dna) {
		for (int i = 0; i < ret.length; i++) {
			if (ret[i] != null) {
				if (dna.sortNum < ret[i].sortNum) {
					//     
					for (int j = ret.length - 1; j > i; j--) {
						ret[j] = ret[j - 1];
					}
					ret[i] = dna;
					break;

				}
			} else {
				ret[i] = dna;
				break;
			}

		}
	}

	//    DNA ，      ，          ，        
	private static class DNA {
		String value;
		int sortNum;
	}

}