归并排序

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class 归并排序 {
    public static int[] tmp = new int[Integer.MAX_VALUE];
    public static void mergeSort(int[] arr, int l, int r){
        if (l >= r){
            return;
        }
        // 确定分界点
        int mid = l + r >> 1;
        int i = l, j = mid + 1;
        // 递归分区间
        mergeSort(arr,l,mid);
        mergeSort(arr,mid+1,r);
        //归并内容
        int k = 0;
        while (i <= mid && j <= r){
            if (arr[i] < arr[j]){
                tmp[k++] = arr[i++];
            }else {
                tmp[k++] = arr[j++];
            }
        }
        while (i <= mid){
            tmp[k++] = arr[i++];
        }
        while (j <= r){
            tmp[k++] = arr[j++];
        }
        // 回归原本数组
        for (int m = 0,n = l; n <= r; m++,n++) {
            arr[n] = tmp[m];
        }
    }
    public static void main(String[] args) throws IOException {
        int n;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        n = Integer.parseInt(br.readLine());
        int[] arr = new int[n];
        String[] strings = br.readLine().split(" ");
        for (int i = 0; i < n; i++) {
            arr[i] = Integer.parseInt(strings[i]);
        }
        mergeSort(arr,0,n-1);
        for (int i = 0; i < n; i++) {
            System.out.print(arr[i]+" ");
        }

    }
}