递归merge排序

package sort;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Scanner;

public class MergeSort {
	public static void merge(int[] arr, int[] tmp, int l_start,
			int r_start, int r_end) {
		int tmp_pos = l_start;
		int l_end = r_start-1;
		int i=l_start;
		int j = r_start;
		while(i<=l_end&&j<=r_end){
			if(arr[i]<arr[j]){
				tmp[tmp_pos++]=arr[i++];
			}
			else{
				tmp[tmp_pos++]=arr[j++];
			}
		}
		while(i<=l_end){
			tmp[tmp_pos++]=arr[i++];
		}

		while(j<=r_end){
			tmp[tmp_pos++]=arr[j++];
		}
		int N = r_end - l_start+1;
		for(int k=0;k<N;k++,r_end--){
			arr[r_end] = tmp[r_end];
		}

	}

	public static void mssort(int[] arr, int[] tmp, int left, int right) {
		if (left < right) {
			int center = (left + right) / 2;
			mssort(arr, tmp, left, center);
			mssort(arr, tmp, center + 1, right);
			merge(arr, tmp, left, center + 1, right);
		}
	}

	public static void main(String[] args) {
		int N;
		Scanner scanner = new Scanner(new BufferedReader(new InputStreamReader(
				System.in)));
		N = scanner.nextInt();
		int[] arr = new int[N];
		int[] tmp = new int[N];
		for (int i = 0; i < N; i++) {
			arr[i] = scanner.nextInt();
		}
		scanner.close();
		mssort(arr,tmp,0,arr.length-1);
		for(int i=0;i<tmp.length;i++){
			System.out.println(tmp[i]);
		}
	}

}