洛谷 P1044 栈（Catalan 数）

一、题目描述

二、算法分析说明

三、AC 代码

#include<cstdio>
#pragma warning(disable:4996)
__int128 n, x = 1;
int main() {
	scanf("%llu", &n);
	for (__int128 i = n + 1; i <= 2 * n; ++i)x *= i;
	for (__int128 i = 2; i <= n; ++i)x /= i;
	printf("%llu\n", x / (n + 1));
	return 0;
}

#include<cstdio>
#pragma warning(disable:4996)
unsigned long long n, x = 1;
int main() {
	scanf("%llu", &n);
	for (unsigned long long i = 1; i <= n; ++i) { x *= i + n, x /= i; }
	printf("%llu\n", x / (n + 1));
	return 0;
}