Codeforces Round #439 B

直接找到规律爆

最多只个数就能使得答案确定为 0 

#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <string>#include <cmath>#include <set>#include <map>#include <stack>#include <queue>#include <ctype.h>#include <vector>#include <algorithm>#include <sstream>#define PI acos(-1.0)#define in freopen("in.txt", "r", stdin)#define out freopen("out.txt", "w", stdout)using namespace std;typedef long long ll;const int maxn = 20 + 7, INF = 0x7f7f7f7f, mod = 1e9 + 7;ll n, m;int main() {    scanf("%I64d %I64d", &n, &m);    ll t = 1;    for(ll i = n+1; i <= n+10 && i <= m; ++i) {        t *= (i%10);        t %= 10;    }    cout << t << endl;    return 0;}