529A And Yet Another Bracket Sequence

#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cctype>
#include<cmath>
#include<cstdlib>
#include<queue>
#include<ctime>
#include<vector>
#include<set>
#include<map>
#include<stack>
using namespace std;
#define uli long long
const uli hsh = 13131;
const uli hsh2 = 19260817;
const uli mod = 1e9+7;
const uli mod2 = 998244353;
int n,m;
string s,t;
char c[1001000];
uli pw[2001000],h[2000100],pw2[2001000],h2[2001000];
int sum[1001000],pre[1001000],sur[1001000],le,ri;
inline pair<uli,uli> v(int l,int r){
    return make_pair((h[r]-(l?h[l-1]:0)*pw[r-l+1]%mod+mod)%mod,
             (h2[r]-(l?h2[l-1]:0)*pw2[r-l+1]%mod2+mod2)%mod2);
}
inline bool ck(int i,int j){
    int l=0,r=m;
    while(r-l>1){
      int mid=(l+r)>>1;
      if(i+mid-1>=m||j+mid-1>=m||v(i,i+mid-1)!=v(j,j+mid-1))r=mid;
        else l=mid;
    }
    if(i+r-1>=m||j+r-1>=m)return 1;
    return t[i+r-1]<t[j+r-1];
}
int main(){
    int i,j,k;
    scanf("%s",c);
    s=c;
    t=s+s;
    n=s.length();
    m=t.length();
    pw[0]=1;
    for(i=1;i<=m;i++)pw[i]=pw[i-1]*hsh%mod;
    h[0]=t[0];
    for(i=1;i<m;i++)h[i]=(h[i-1]*hsh+t[i])%mod;
    pw2[0]=1;
    for(i=1;i<=m;i++)pw2[i]=pw2[i-1]*hsh2%mod2;
    h2[0]=t[0];
    for(i=1;i<m;i++)h2[i]=(h2[i-1]*hsh2+t[i])%mod2;
    for(i=0;i<n;i++)sum[i]=(i?sum[i-1]:0)+(s[i]==‘(‘?1:-1);
    pre[0]=sum[0],sur[n-1]=sum[n-1];
    for(i=1;i<n;i++)pre[i]=min(sum[i],pre[i-1]);
    for(i=n-2;i>=0;i--)sur[i]=min(sum[i],sur[i+1]);
    int maxl=1e9+7,pl=-1;
    if(sum[n-1]<0)le=-sum[n-1];
      else ri=sum[n-1];
    for(i=0;i<n;i++){
      k=(i?sum[i-1]:0);
      int w=min(sur[i]-k,sum[n-1]-k+(i?pre[i-1]:0));//重点!!!
      int ll=max(-w,max(0,-sum[n-1]));
      if(ll+ri+n<maxl){
          maxl=ll+ri+n;
          le=ll;
          pl=i;
      }else if(ll+ri+n==maxl&&ck(i,pl)){
          pl=i;
      }
    }
    for(i=1;i<=le;i++)cout<<"(";
    for(i=pl;i<n;i++)cout<<s[i];
    for(i=0;i<pl;i++)cout<<s[i];
    for(i=1;i<=ri;i++)cout<<")";
    return 0;
}