归并排序

Posted 2021-10-12 Tianyiya H.T.W

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import java.util.Scanner;

public class Main {

    public static void sort(int [] arr,int left,int right) {
        if (left >= right) {
            return;
        }

        int m = (left + right) >>> 1;

        sort(arr, left, m);
        sort(arr, m + 1, right);

        int[] tmp = new int[right - left + 1];

        int i = left, j = m + 1, index = 0;

        while (i <= m && j <= right) {

            if (arr[i] <= arr[j]) {
                tmp[index ++] = arr[i ++];
            } else {
                tmp[index ++] = arr[j ++];
            }
        }

        while (i <= m) {
            tmp[index ++] = arr[i ++];
        }

        while (j <= right) {
            tmp[index ++] = arr[j ++];
        }

        for (int k = left; k <= right; ++ k) {
            arr[k] = tmp[k - left];
        }
    }

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        while (in.hasNext()) {

            int n = in.nextInt();

            int[] arr = new int[n];

            for (int i = 0; i < n; ++ i) {
                arr[i] = in.nextInt();
            }

            sort(arr, 0, n - 1);

            System.out.print(arr[0]);

            for (int i = 1; i < n; ++ i) {
                System.out.print(" " + arr[i]);
            }

            System.out.println();
        }
    }
}

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