Submission #586899

#	Time	Username	Problem	Language	Result	Execution time	Memory
586899		Bench0310	Flood (IOI07_flood)	C++17	100 / 100	523 ms	31180 KiB

flood

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

const int N=100001;
array<int,2> points[N];
array<int,3> hot_pos[4*N];
array<int,2> walls[2*N];
array<int,2> wall_hots[2*N];
array<int,2> edges[16*N];
int edges_idx=0;
int edges_start[4*N];
array<int,2> prv[N+1];
array<int,4> events[5*N];
int events_idx=0;
int cc_id[4*N];
int d[4*N];
int res_idx=0;

int que[4*(N+5)];
int qid=0;
int qsz=0;

void ini_queue(){qid=qsz=0;}
void push_queue(int a){que[qsz++]=a;}
int front_queue()
{
    if(qid<qsz) return que[qid++];
    else return -1;
}

void update(int idx,int l,int r,int ql,int qr,int x)
{
    if(ql>qr) return;
    if(l==ql&&r==qr) que[idx]=x;
    else
    {
        int m=(l+r)/2;
        update(2*idx,l,m,ql,min(qr,m),x);
        update(2*idx+1,m+1,r,max(ql,m+1),qr,x);
    }
}

int query(int idx,int l,int r,int pos)
{
    if(l==r) return que[idx];
    int m=(l+r)/2;
    if(pos<=m) return max(que[idx],query(2*idx,l,m,pos));
    else return max(que[idx],query(2*idx+1,m+1,r,pos));
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    //set up points
    int n;
    cin >> n;
    for(int i=1;i<=n;i++)
    {
        auto &[x,y]=points[i];
        cin >> x >> y;
    }
    //x_compress
    for(int i=1;i<=n;i++) que[i]=i;
    sort(que+1,que+n+1,[&](int a,int b){return (points[a][0]<points[b][0]);});
    int hx=0;
    for(int i=1;i<=n;i++)
    {
        if(i>1&&points[que[i-1]][0]!=points[que[i]][0]) hx++;
        edges_start[que[i]]=hx;
    }
    for(int i=1;i<=n;i++) points[i][0]=edges_start[i];
    //y_compress
    sort(que+1,que+n+1,[&](int a,int b){return (points[a][1]<points[b][1]);});
    int hy=0;
    for(int i=1;i<=n;i++)
    {
        if(i>1&&points[que[i-1]][1]!=points[que[i]][1]) hy++;
        edges_start[que[i]]=hy;
    }
    for(int i=1;i<=n;i++) points[i][1]=edges_start[i];
    //set up hots
    int hot_cnt=0;
    auto add_hot=[&](int x,int y)->int
    {
        hot_cnt++;
        hot_pos[hot_cnt]={x,y,hot_cnt};
        return hot_cnt;
    };
    for(int i=1;i<=n;i++)
    {
        auto &[x,y]=points[i];
        for(int j=0;j<=1;j++) for(int k=0;k<=1;k++) add_hot(x+j,y+k);
    }
    //set up walls
    int m;
    cin >> m;
    for(int i=1;i<=m;i++)
    {
        auto &[a,b]=walls[i];
        cin >> a >> b;
        if(points[a]>points[b]) swap(a,b);
        if(points[a][0]==points[b][0]) wall_hots[i]={4*(a-1)+2,4*(a-1)+4};
        else wall_hots[i]={4*(a-1)+3,4*(a-1)+4};
    }
    //set up hots' edges
    auto add_edge=[&](int a,int b)
    {
        edges[edges_idx++]={a,b};
        edges[edges_idx++]={b,a};
    };
    auto process=[&]()
    {
        //extract edges
        fill(que,que+4*(N+5),-1);
        for(int i=0;i<=N;i++) prv[i]={-1,-1}; //x,hot_id
        events_idx=0; //x,tp,[y,hot_id] or [yl,yr]
        for(int i=1;i<=hot_cnt;i++) events[events_idx++]={hot_pos[i][0],0,hot_pos[i][1],i};
        for(int i=1;i<=m;i++)
        {
            auto [a,b]=walls[i];
            auto [xa,ya]=points[a];
            auto [xb,yb]=points[b];
            if(xa==xb) events[events_idx++]={xa,1,ya+1,yb};
        }
        sort(events,events+events_idx);
        for(int i=0;i<events_idx;i++)
        {
            auto [x,tp,yl,yr]=events[i];
            if(tp==0)
            {
                int w=query(1,0,N,yl);
                auto [px,pid]=prv[yl];
                if(w<px) add_edge(yr,pid);
                prv[yl]={x,yr};
            }
            else update(1,0,N,yl,yr,x);
        }
        //flip coordinates
        for(int i=1;i<=n;i++) swap(points[i][0],points[i][1]);
        for(int i=1;i<=hot_cnt;i++) swap(hot_pos[i][0],hot_pos[i][1]);
    };
    process();
    process();
    int cc_cnt=0;
    ini_queue();
    sort(edges,edges+edges_idx);
    for(int i=edges_idx-1;i>=0;i--) edges_start[edges[i][0]]=i;
    //find hots' components
    for(int i=1;i<=hot_cnt;i++)
    {
        if(cc_id[i]!=0) continue;
        cc_cnt++;
        auto add=[&](int a)
        {
            if(cc_id[a]==0)
            {
                cc_id[a]=cc_cnt;
                push_queue(a);
            }
        };
        add(i);
        while(1)
        {
            int a=front_queue();
            if(a==-1) break;
            for(int j=edges_start[a];j<edges_idx&&edges[j][0]==a;j++) add(edges[j][1]);
        }
    }
    //set up cc's edges
    edges_idx=0;
    for(int i=1;i<=m;i++)
    {
        auto [a,b]=wall_hots[i];
        edges[edges_idx++]={cc_id[a],cc_id[b]};
        edges[edges_idx++]={cc_id[b],cc_id[a]};
    }
    sort(edges,edges+edges_idx);
    for(int i=edges_idx-1;i>=0;i--) edges_start[edges[i][0]]=i;
    sort(hot_pos+1,hot_pos+hot_cnt+1);
    ini_queue();
    auto add=[&](int a,int nd)
    {
        if(d[a]==0)
        {
            d[a]=nd;
            push_queue(a);
        }
    };
    for(int i=1;i<=hot_cnt;i++)
    {
        auto [x,y,hot]=hot_pos[i];
        add(cc_id[hot],1);
        while(1)
        {
            int a=front_queue();
            if(a==-1) break;
            for(int j=edges_start[a];j<edges_idx&&edges[j][0]==a;j++) add(edges[j][1],d[a]+1);
        }
    }
    for(int i=1;i<=m;i++)
    {
        auto [a,b]=wall_hots[i];
        if(d[cc_id[a]]==d[cc_id[b]]) edges_start[res_idx++]=i;
    }
    cout << res_idx << "\n";
    for(int i=0;i<res_idx;i++) cout << edges_start[i] << "\n";
    return 0;
}

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 10 / 10
• Subtask 4: 3 / 3
• Subtask 5: 10 / 10
• Subtask 6: 3 / 3
• Subtask 7: 3 / 3
• Subtask 8: 3 / 3
• Subtask 9: 3 / 3
• Subtask 10: 9 / 9
• Subtask 11: 9 / 9
• Subtask 12: 9 / 9
• Subtask 13: 9 / 9
• Subtask 14: 9 / 9