Digit Division（排列组合+思维）（Gym 101480D ）

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

char a[300005];

ll qpow(ll x,ll m)
{
    ll ans = 1;
    while(m)
    {
        if(m % 2 == 1)
        {
            ans *= x;
            ans %= 1000000007;
        }
        x *= x;
        x %= 1000000007;
        m /= 2;
    }
    return ans;
}

int main()
{
    ll n, m,num = 0,i;
    scanf("%lld%lld",&n,&m);
    scanf("%s", a);
    ll x = 0;
    for(i = 0; i < n; i++)
    {
        x *= 10;
        x += a[i] - '0';
        x %= m;
        if(x == 0) num++;
    }
    ll ans;
    if(x == 0)
     ans = qpow(2,num-1);
    else ans = 0;
    printf("%lld\n",ans);
    return 0;
}