整数二分

注意一下l和r的范围即可

import java.util.*;

public class Main {
    static final int N = 100010;
    static int[] a = new int[N];
    static int n, q;

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

        n = sc.nextInt(); q = sc.nextInt();
        sc.nextLine();

        String[] s = sc.nextLine().split(" ");
        for (int i = 0; i < n; i++) a[i] = Integer.parseInt(s[i]);

        while (q -- > 0) {
            int k = sc.nextInt();

            int l = 0, r = n - 1;
            while (l < r) {
                int mid = l + r >> 1;
                if (a[mid] >= k) r = mid;
                else l = mid + 1;
            }
            if (a[l] != k) {
                System.out.println("-1 -1");
                continue;
            }
            System.out.print(l + " ");

            l = 0; r = n - 1;
            while (l < r) {
                int mid = l + r + 1 >> 1;
                if (a[mid] <= k) l = mid;
                else r = mid - 1;
            }
            System.out.println(l);
        }
    }
}