代码逻辑是没有问题的，一般这种情况开 O2 就能解决（原理我不知道），发现你数组开小了，修改代码：
```
#include<bits/stdc++.h>
using namespace std;
int a[100000],len;
void fac(int n){
int carry = 0;
for(int i = 1; i <= len; i++){
a[i] = a[i]*n + carry;
carry = a[i]/10;
a[i] %= 10;
}
while(carry > 0){
a[++len] = carry%10;
carry /= 10;
}
}
int main(){
int t,n,a1;
cin >> t;
for(int k = 1; k <= t; k++){
int cnt = 0;
len = 1;
memset(a,0,sizeof(a));
a[1] = 1;
cin >> n >> a1;
for(int i = 1; i <= n; i++) fac(i);
for(int i = len; i >= 1; i--){
if(a1 == a[i]) cnt++;
}
cout << cnt << endl;
}
return 0;
}
```
by sfqxx1 @ 2023-11-17 22:00:27
@[zhouzihang1](/user/827018) 开 O2 过了
by sfqxx1 @ 2023-11-17 22:01:02
哦，抱歉，没仔细看代码，以为写的int
by zhouzihang1 @ 2023-11-17 22:02:05
@[sfqxx1](/user/934014) 感谢感谢
by letusgo @ 2023-11-17 23:31:27
我这更神奇，我关了O2结果0分变全AC了？
by DaD114514 @ 2024-01-12 08:45:37