AcWing789.cpp

#include <iostream>
using namespace std;
int a[100005];
int main()
{
    int n,q,k;
    scanf("%d%d", &n, &q);
    for (int i=0; i<n; i++)scanf("%d", &a[i]);
    while (q-->0)
    {
        scanf("%d", &k);
        int l = 0, r = n - 1;
        while (l < r)
        {
            int mid = (l + r) / 2;
            if (a[mid] >= k)
            {
                r = mid;
            }
            else
            {
                l = mid + 1;
            }
        }
        if(a[l]!=k)
        {
            printf("-1 -1\n");
        }
        else
        {
            printf("%d ", l);
            int l = 0, r = n - 1;
            while (l < r)
            {
                int mid = (l + r + 1) / 2;
                if (a[mid] <= k)
                {
                    l = mid;
                }
                else
                {
                    r = mid - 1;
                }
            }
            printf("%d\n", l);
        }
    }
    
}