Python(2.7.3) 解法, 执行用时: 237ms, 内存消耗: 32108K, 提交时间: 2018-04-06 19:37:01

mod = 998244353
p = int(raw_input())

def fac(n, mod):
    ret = 1
    for i in range(2, n + 1):
        ret = ret * i % mod
    return ret

print fac(p, mod) * fac(p, mod) * 2 % mod

C++14(g++5.4) 解法, 执行用时: 9ms, 内存消耗: 408K, 提交时间: 2020-07-11 20:59:07

#include<cstdio>
int main()
{
    long long ans=2,n;
    scanf("%lld",&n);
    for(int i=2;i<=n;i++)
    ans*=i,ans%=998244353,ans*=i,ans%=998244353;
    printf("%lld\n",ans);
}

Python3(3.5.2) 解法, 执行用时: 209ms, 内存消耗: 3560K, 提交时间: 2018-04-06 19:33:32

mod = 998244353


def pp(n):
    ret = 1
    for i in range(n):
        ret *= i + 1
        ret %= mod
    return ret

n = int(input())
ans = pp(n) ** 2 * 2 % mod
print(ans)

C++11(clang++ 3.9) 解法, 执行用时: 13ms, 内存消耗: 496K, 提交时间: 2020-02-29 15:04:14

#include<cstdio>
int main()
{
	long long ans=2,n;
	scanf("%lld",&n);
	for(int i=2;i<=n;i++)
	ans*=i,ans%=998244353,ans*=i,ans%=998244353;
	printf("%lld\n",ans);
}