你这时间复杂度$O(n^2)$过得了1e5?
by 歌吟入梦 @ 2019-11-23 14:21:12
@[实哥](/user/54153) 那用卡特兰数能过吗
by The_Star @ 2019-11-23 14:23:57
@[The_Star](/user/250171) 我的代码跟你的差不多 , 情况跟你一样
```cpp
#include<iostream>
using namespace std;
long long f[114514];
const int mod = 1e9 + 7;
int main()
{
int a;
cin >> a;
f[0] = f[1] = 1;
for(int i = 2;i <= a;i++)
for(int j = 0;j < i;j++)
f[i] = ((f[j] * f[i - j - 1]) % mod + f[i]) % mod;
cout << f[a] % mod;
return 0;
}
```
by ZackofZHOU @ 2023-09-02 11:31:37
最后两个点TLE , 其他都AC
by ZackofZHOU @ 2023-09-02 11:32:54