LOJ #2034. 「SDOI2016」排列计数

题目链接：传送门
这种题就应该一眼秒掉才对

有个数是稳定的，也就是说
有个数要做错排
那就是从个数里挑个数做错排，为错排数组
可是数组初始化在全局里LOJ就说我超内存直接CE
为啥为啥

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <complex>
#include <algorithm>
#include <climits>
#include <queue>
#include <map>
#include <set>
#include <vector>
#include <iomanip>
#define A 1000010
#define B 2010

using namespace std;
typedef long long ll;
const int mod = 1e9 + 7;
ll n, m, f[A], fac[A]; int T;
ll fpow(ll a, ll b, ll ans = 1) {
    while (b) {
        if (b & 1) ans = ans * a % mod;
        a = a * a % mod;
        b >>= 1;
    }
    return ans;
}
ll C(ll n, ll m) {
    return fac[n] * fpow(fac[m] * fac[n - m] % mod, mod - 2) % mod;
}
ll lucas(ll n, ll m) {
    return m ? C(n % mod, m % mod) * lucas(n / mod, m / mod) % mod : 1;
}

int main(int argc, char const *argv[]) {
    cin >> T; f[2] = fac[0] = fac[1] = 1; fac[2] = 2;
    for (int i = 3; i <= 1000000; i++) f[i] = (f[i - 1] + f[i - 2]) % mod * (i - 1) % mod, fac[i] = fac[i - 1] * (ll)i % mod;
    while (T--) {
        scanf("%lld%lld", &n, &m);
        if (n == m) puts("1");
        else printf("%lld\n", lucas(n, n - m) * f[n - m] % mod);
    }
}