dfs()暴搜----CodeForce 1143B

題意：

#include<bits/stdc++.h>
using namespace std;
#define ll long long
ll dfs(ll n)
{
    if (n == 0) return 1;
    if (n < 10) return n;
    return max(dfs(n / 10) * (n % 10), dfs(n / 10 - 1) * 9);
}

int main()
{
    ll n;
    cin>>n;
    cout<<dfs(n)<<endl;

}