C++(g++ 7.5.0) 解法, 执行用时: 73ms, 内存消耗: 24812K, 提交时间: 2023-04-29 17:15:53

#include<bits/stdc++.h>
using namespace std;
#define M 2000010
#define mod 998244353
int n,f[M],g[M],inv[M];
int main()
{
	f[1]=g[1]=inv[1]=1;
	for(int i=2;i<2000005;i++){
		f[i]=1ll*f[i-1]*i%mod;
		inv[i]=1ll*(mod-mod/i)*inv[mod%i]%mod;
		g[i]=1ll*g[i-1]*inv[i]%mod;
	}
	while(~scanf("%d",&n))
printf("%d\n",1ll*g[2*n+1]*f[n]%mod*f[n]%mod);
	return 0;
}

C++(clang++ 11.0.1) 解法, 执行用时: 301ms, 内存消耗: 48736K, 提交时间: 2023-05-04 20:53:53

#include<bits/stdc++.h>
using namespace std;
const int mod=998244353,mxn=2e6+10;;
long long n,f[mxn],g[mxn],a[mxn];
int main(){
	f[1]=g[1]=a[1]=1;
	for(int i=2;i<mxn;i++){
		f[i]=f[i-1]*i%mod;
		a[i]=(mod-mod/i)*a[mod%i]%mod;
		g[i]=g[i-1]*a[i]%mod;
	}
	while(cin>>n) cout<<g[2*n+1]*f[n]%mod*f[n]%mod<<'\n';
	return 0;
}

pypy3 解法, 执行用时: 554ms, 内存消耗: 41320K, 提交时间: 2023-04-29 13:23:07

Mod = 998244353

fact = [0] * 2000010
fact[0] = 1
for i in range(1, 2000003):
    fact[i] = i * fact[i - 1] % Mod
    

while True:
    try:
        n = int(input())
        ans = fact[n] * fact[n] % Mod * pow(fact[2 * n + 1], Mod - 2, Mod) % Mod
        print(ans)
    except EOFError:
        break

Python3(3.5.2) 解法, 执行用时: 1140ms, 内存消耗: 83704K, 提交时间: 2020-07-13 09:49:26

import sys

fact = [1] * (2000007)
for i in range(1, 2000007):
    fact[i] = fact[i - 1] * i % 998244353
for line in sys.stdin:
    sys.stdout.write('%d\n' % (fact[int(line)] ** 2 * pow(fact[2 * int(line) + 1], 998244351, 998244353) % 998244353))