Submission #1237626

#	Time	Username	Problem	Language	Result	Execution time	Memory
1237626		hamanp87	Monochrome Points (JOI20_monochrome)	C++17	100 / 100	982 ms	10332 KiB

monochrome

#include<bits/stdc++.h>
using namespace std;
using ll=long long;

//#pragma GCC optimize("03,unroll-loops")
//#pragma GCC target("avx2")
//#pragma GCC target("sse4")

#define all(v) v.begin(),v.end()
#define F first
#define S second
#define pub push_back
#define pob pop_back
#define puf push_front
#define pof pop_front
//#define randi uniform_int_distribution<long long>
#define damoon(v) v.resize(unique(all(v))-v.begin())
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//randi dist(0,10000000000000000);

typedef pair<int,int> pii;
typedef pair<long long,long long> pll;
typedef pair<int,bool> pib;
typedef pair<long long,bool> plb;
typedef pair<int,pii> pip;
typedef pair<pii,int> ppi;
typedef vector<int> veci;
typedef vector<long long> vecl;
typedef vector<bool> vecb;
typedef vector<pii> vecp;
typedef set<int> seti;
typedef set<long long> setl;
typedef set<pii> setp;
typedef map<int,int> mapii;
typedef map<long long,long long> mapll;
typedef map<int,bool> mapib;
typedef map<long long,bool> maplb;

const int inf=1e9,mod=1e9+7,neginf=-1e9,N=4e5+5;
const double PI=acos(-1);

struct Fenwick
{
    veci f;
    int n;
    Fenwick(int m)
    {
        n=m;
        f.assign(n+1,0);
    }

    void update(int i,int v)
    {
        for(++i;i<=n;i+=i&-i)
            f[i]+=v;
    }

    int get(int i)
    {
        int s=0;
        for(++i;i>0;i-=i&-i)
            s+=f[i];

        return s;
    }
};

int n;
ll krj[N];
veci b,w;

inline ll res(int i,Fenwick &Fen)
{
    if(krj[i]!=-1)
        return krj[i];

    vecp v;
    for(int j=0;j<n;j++)
        v.pub(pii(min(b[j],w[(j+i)%n]),max(b[j],w[(j+i)%n])));

    sort(all(v),greater<>());
    ll ret=0;
    for(int j=0;j<n;j++)
    {
        ret+=Fen.get(v[j].S);
        Fen.update(v[j].F+0,+1);
        Fen.update(v[j].S+1,-1);
    }
    for(int j=0;j<n;j++)
    {
        Fen.update(v[j].F+0,-1);
        Fen.update(v[j].S+1,+1);
    }

    return krj[i]=ret;
}

void solve()
{
    cin>>n;
    for(int i=0;i<2*n;i++)
    {
        char c;
        cin>>c;
        if(c=='B')
            b.pub(i);
        else
            w.pub(i);
    }

    memset(krj,-1,sizeof(krj));
    Fenwick Fen(N);
    int L=0,R=n;

    while(L<R)
    {
        int mid=(L+R)>>1;

        if(res(mid,Fen)<res(0,Fen))
        {
            if(res(0,Fen)>res(1,Fen))
            {
                L=mid+1;
            }
            else
            {
                R=mid-1;
            }
        }
        else
        {
            if(res(mid,Fen)<res(mid+1,Fen))
            {
                L=mid+1;
            }
            else
            {
                R=mid-0;
            }
        }
    }

    cout<<res(L,Fen)<<"\n";
}

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

    //ifstream fin("in.txt");
    //ofstream fout("out.txt");

    int t=1;
    //cin>>t;
    while(t--)
    {
        solve();
    }
}

• Subtask 1: 4 / 4
• Subtask 2: 21 / 21
• Subtask 3: 10 / 10
• Subtask 4: 65 / 65