UVA 1584 / Hashing Rotation

/***
 created: 2022-06-19-23.41.40
***/

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename U> using ordered_set=tree<U, null_type,less<U>,rb_tree_tag,tree_order_statistics_node_update>;
#define ll long long
#define ull unsigned long long
#define test int tt; cin>>tt; for(int cs=1;cs<=tt;cs++)
#define get_lost_idiot return 0
#define nl '\n'

ull p[200005];
ull hash1[200005];
ull rhash1[200005];
ull base=307;

void power()
{
    p[0]=1;
    for(int i=1;i<=200003;i++)
    {
        p[i]=p[i-1]*base;
    }
}

void hashing(string a)
{
    hash1[0]=0;
    for(int i=1; i<=a.size(); i++)
    {
        hash1[i]=(hash1[i-1]*base+a[i-1]);
    }

    rhash1[a.size()+1]=0;
    for(int i=a.size(); i>=1;i--)
    {
        rhash1[i]=(rhash1[i+1]*base + a[i-1]);
    }
}

ull forwardhash(ll l,ll r)
{
    return (hash1[r] - (hash1[l-1] * p[r-l+1]));
}

ull backwardhash(ll l,ll r)
{
    return (rhash1[l] - (rhash1[r+1] * p[r-l+1]));
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    power();

    test
    {
        ll n,m,i,j,k,l,h;

        string a;

        cin>>a;

        n=a.size();

        a+=a;

        hashing(a);

        k=1;

        for(i=2;i<=n;i++)
        {
             l=0,h=n-1;

             while(l<=h)
             {
                  ll mid=(l+h)/2;

                  if(forwardhash(k,k+mid)==forwardhash(i,i+mid))
                  {
                       l=mid+1;
                  }
                  else
                  {
                       h=mid-1;
                  }
             }

             if(l<=n-1)
             {
                  if(a[i+l-1]<a[k+l-1])
                  {
                       k=i;
                  }
             }
        }

        cout<<a.substr(k-1,n)<<nl;

    }

    get_lost_idiot;
}