找了半天找到问题了
before:
```
ll exgcd(ll a, ll b, ll &x, ll &y){
if (!b) {
x = 1;
y = 0;
return a;
}
int d = exgcd(b, a % b, x, y);
int t = x;
x = y;
y = t - (a / b) * y;
return d;
}
```
after:
```
ll exgcd(ll a, ll b, ll &x, ll &y){
if (!b) {
x = 1;
y = 0;
return a;
}
ll d = exgcd(b, a % b, x, y);
ll t = x;
x = y;
y = t - (a / b) * y;
return d;
}
```
by x383494 @ 2023-02-25 20:20:28