Submission #1095608

#	Time	Username	Problem	Language	Result	Execution time	Memory
1095608		simona1230	Joker (BOI20_joker)	C++17	0 / 100	306 ms	19872 KiB

Joker

#include <bits/stdc++.h>

using namespace std;

int n,m,k;
pair<int,int> e[200001],q[200001];

void read()
{
    cin>>n>>m>>k;
    for(int i=1;i<=m;i++)
    {
        int x,y;
        cin>>x>>y;
        e[i]={x,y};
    }

    for(int i=1;i<=k;i++)
    {
        int l,r;
        cin>>l>>r;
        q[i]={l,r};
    }
}

struct event
{
    int x,y;
    pair<int,int> p;
    event(){}
    event(int _x,int _y,pair<int,int> _p)
    {
        x=_x;
        y=_y;
        p=_p;
    }
};

pair<int,int> p[200001];
stack<event> s;
int sz[200001];

void rollback()
{
    event t=s.top();
    s.pop();

    p[t.x]=t.p;
    sz[t.y]-=sz[t.x];
}

pair<int,int> parent(int x)
{
    if(x==p[x].first)return p[x];
    pair<int,int> curr=parent(p[x].first);
    curr.second+=p[x].second;
    return curr;
}

void unite(int x,int y,int&cnt, bool&cyc)
{
    //cout<<x<<" "<<y<<endl;
    pair<int,int> px=parent(x);
    pair<int,int> py=parent(y);

    x=px.first;
    y=py.first;

    if(x!=y)
    {
        if(sz[x]>sz[y])swap(x,y);
        s.push({x,y,p[x]});
        p[x]={y,px.second+py.second+1};
        sz[y]+=sz[x];
        cnt++;
    }
    else
    {
        if(px.second%2==py.second%2)
        {
            //cout<<"hje"<<endl;
            cyc=1;
        }
    }
}

int c[200001];

void rec(int l,int r,int optl,int optr)
{
    if(l>r)return;
    //cout<<l<<" "<<r<<" "<<optl<<" "<<optr<<endl;
    if(optl==optr)
    {
        for(int i=l;i<=r;i++)
            c[i]=optr;
        return;
    }

    int mid=(l+r)/2;

    int cnt1=0;
    bool ans=0;
    for(int i=l;i<mid;i++)
        unite(e[i].first,e[i].second,cnt1,ans);

    int j=optr;
    int cnt2=0;
    while(!ans&&j>=optl)
    {
        if(j!=m+1)
            unite(e[j].first,e[j].second,cnt2,ans);
        j--;
    }
    j++;

    while(cnt2)
    {
        cnt2--;
        rollback();
    }

    while(cnt1)
    {
        cnt1--;
        rollback();
    }

    c[mid]=j;
    //cout<<"! "<<mid<<" "<<j<<endl;

    ans=0;
    int cnt3=0;
    for(int i=j+1;i<=min(m,optr);i++)
        unite(e[i].first,e[i].second,cnt3,ans);
    if(ans)rec(l,mid-1,j,j);
    else rec(l,mid-1,optl,j);

    while(cnt3)
    {
        cnt3--;
        rollback();
    }

    ans=0;
    int cnt4=0;
    for(int i=l;i<=mid;i++)
        unite(e[i].first,e[i].second,cnt4,ans);
    if(ans)rec(mid+1,r,optr,optr);
    else rec(mid+1,r,j,optr);

    while(cnt4)
    {
        cnt4--;
        rollback();
    }
}

void solve()
{
    for(int i=1;i<=k;i++)
    {
        if(q[i].second<c[q[i].first])cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	read();
	for(int i=1;i<=n;i++)
        p[i]={i,0},sz[i]=1;
    rec(1,m,1,m+1);
	solve();

	return 0;
}
/*
6 8 2
1 3
1 5
1 6
2 5
2 6
3 4
3 5
5 6

1 8
8 8
*/

• Subtask 1: 0 / 6
• Subtask 2: 0 / 8
• Subtask 3: 0 / 25
• Subtask 4: 0 / 10
• Subtask 5: 0 / 22
• Subtask 6: 0 / 29