UVA 10474 - Where is the Marble Timelimit

Question

I got a problem from UVA online judge Problem link. I have read it tons of times and as they said, I have to get the answer really fast.

I have used a binary search and STD::Sort, but I am still having time error. I don't know any faster way to search on an array than binary search.

Any feedback please?

PS:I am not an english speaker, sorry for my english.

#include <stdio.h>
#include <string>
#include <algorithm>

int n,q,vec[100000];
int inicio,final,medio,busca;
int cont;
int busquedabinaria()
{

    //busqueda binaria
    std::sort(vec,vec+n);
    inicio=0;
    final=n-1;
    medio=(inicio+final)/2;

    while(inicio<=final)
    {
        if(vec[inicio]==busca)
            return inicio;
        if(vec[medio]==busca)
            return medio;
        if(vec[final]==busca)
            return final;
        medio = (inicio + final) / 2;
        if (vec[medio] > busca)
            final = medio - 1;
        else if (vec[medio] < busca)
            inicio = medio + 1;
        // found

    }
    return -1;

}

int main() 
{

    freopen("in.txt", "rt",stdin);
    freopen("out.txt", "wt",stdout);

    while (scanf("%d %d\n",&n,&q)!=EOF && (n!=0 || q!=0)    )
    {
        for (int i=0;i<n;i++)
        {
            scanf("%d\n",&vec[i]);

        }
        printf("CASE# %d:\n",cont+1);
        cont++;
        while(q--)
        {

        scanf("%d\n",&busca);

            int res=busquedabinaria();
            if(res!=-1)
            {
                while (vec[res-1]==busca && res>0)
                {
                    res--;
                }
                printf("%d found at %d\n",busca,res+1);

        }
            else 
                printf("%d not found\n",busca);

        }

    }

    return 0;
}