不用回了，刚AC
```cpp
#include<iostream>
#include<cstring>
using namespace std;
char a[1000010];
long long ans, l, r;
int main() {
cin >> a;
int len = strlen(a);
for (int i = 0; i < len; i++) {
if (a[i] == '(') {
l++;
ans++;
}
else if (ans != 0 && a[i] == ')') {
ans--;
}
if (a[i] == ')') {
r++;
}
}
if (ans != 0 || r != l) {
cout << "NO";
}
else {
cout << "YES";
}
return 0;
}
```
by not_much @ 2024-02-13 11:05:42