Submission #861937

#	Time	Username	Problem	Language	Result	Execution time	Memory
861937		HuyQuang_re_Zero	Flood (IOI07_flood)	C++14	64 / 100	302 ms	45588 KiB

flood

#include <bits/stdc++.h>
#define ll long long
#define db long double
#define N 400005
#define II pair <int,int>
#define III pair <ll,II>
#define IV pair <vector <int>,vector <int> >
#define fst first
#define snd second
#define BIT(x,i) ((x>>i)&1)
#define Log(x) (31-__builtin_clz((int)x))
#define LogLL(x) (63-__builtin_clzll((ll)x))
#define pi acos(-1)
#define to_radian(x) (x*pi/180.0)
#define to_degree(x) (x*180.0/pi)
using namespace std;
struct point { int x,y; } a[100005];
pair <int,int> e[200005];
int n,m,i,u,v,nangle,f[N],mx[100005],ok,alone[100005];
bool visited[100005];
vector <int> angle_to_side[200005][2],adj[400005];
int main()
{
   // freopen("flood.inp","r",stdin);
 //   freopen("flood.out","w",stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cin>>n;
    for(i=1;i<=n;i++) cin>>a[i].x>>a[i].y;
    cin>>m;
    for(i=1;i<=m;i++)
    {
        cin>>u>>v;
        if(a[u].x>a[v].x || (a[u].x==a[v].x && a[u].y>a[v].y)) swap(u,v);
        e[i]={ u,v };
        adj[u].push_back(v);
        adj[v].push_back(u);
    }
    auto BFS_point=[&](int u)
    {
        queue <int> q;
        vector <int> node;
        int ma=0;
        q.push(u); visited[u]=1;
        while(q.size()>0)
        {
            int u=q.front(); q.pop();
            ma=max(ma,a[u].x);
            node.push_back(u);
            for(int v:adj[u])
                if(visited[v]==0) q.push(v),visited[v]=1;
        }
        for(int u:node) mx[u]=ma;
    };
    for(u=1;u<=n;u++)
        if(visited[u]==0) BFS_point(u);


    for(u=1;u<=n;u++) adj[u].clear();
    for(i=1;i<=m;i++)
    {
        int u=e[i].fst,v=e[i].snd;
        if(a[v].x>a[u].x) adj[u].push_back(i),adj[v].push_back(i);
        if(a[v].y>a[u].y) adj[u].push_back(i),adj[v].push_back(i);
    }


    for(u=1;u<=n;u++)
    {
        vector <II> vec;
        for(int x:adj[u])
        {
            int v=(e[x].fst==u ? e[x].snd : e[x].fst),k;
            if(a[u].y<a[v].y) k=1;
            if(a[u].x<a[v].x) k=2;
            if(a[u].y>a[v].y) k=3;
            if(a[u].x>a[v].x) k=4;
            vec.push_back({ x,k });
        }
        adj[u].clear();
        sort(vec.begin(),vec.end(),[&](II a,II b){ return a.snd<b.snd; });
        if(vec.size()==0) continue;
        else if(vec.size()==1)
        {
            II x=vec.back();
            alone[u]=++nangle;
            for(i=0;i<=1;i++)
                angle_to_side[x.fst][i].push_back(nangle);
        }
        else
        {
            auto consider=[&](II a,II b)
            {
                int oka=(a.snd==1 || a.snd==4),okb=(b.snd==2 || b.snd==3);
                nangle++;
                angle_to_side[a.fst][oka].push_back(nangle);
                angle_to_side[b.fst][okb].push_back(nangle);
            };
            for(i=1;i<vec.size();i++)
                consider(vec[i-1],vec[i]);
            consider(vec.back(),vec[0]);
        }
    }
    for(u=1;u<=n;u++) adj[u].clear();

    for(i=1;i<=m;i++)
    {
        for(ok=0;ok<=1;ok++)
        {
            u=angle_to_side[i][ok][0],v=angle_to_side[i][ok][1];
            adj[u].push_back(v),adj[v].push_back(u);
        }
        u=angle_to_side[i][0][0],v=angle_to_side[i][1][0];
        adj[u].push_back(v+nangle),adj[v].push_back(u+nangle);
    }


    memset(f,63,sizeof(f));
    set <pair <int,int> > s;
    for(i=1;i<=m;i++)
    {
        int u=e[i].fst,v=e[i].snd;
        if(a[v].x==mx[v])
        {
            if(a[u].x==a[v].x)
                for(int u:angle_to_side[i][1])
                    s.insert({ 0,u }),f[u]=0;
            else if(alone[v]>0)
                s.insert({ 0,alone[v] }),f[alone[v]]=0;
        }
    }
    while(s.size()>0)
    {
        int u=s.begin()->snd; s.erase(s.begin());
        for(int x:adj[u])
        {
            int v,k;
            if(x<=nangle) v=x,k=0; else v=x-nangle,k=1;
            if(f[v]>f[u]+k)
            {
                s.erase({ f[v],v });
                f[v]=f[u]+k;
                s.insert({ f[v],v });
            }
        }
    }
    int res=0;
    for(i=1;i<=m;i++)
    {
        int u=angle_to_side[i][0][0],v=angle_to_side[i][1][0];
        if(f[u]==f[v]) res++;
    }
    cout<<res<<'\n';
    for(i=1;i<=m;i++)
    {
        int u=angle_to_side[i][0][0],v=angle_to_side[i][1][0];
        if(f[u]==f[v]) cout<<i<<'\n';
    }
}

Compilation message (stderr)

flood.cpp: In function 'int main()':
flood.cpp:99:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   99 |             for(i=1;i<vec.size();i++)
      |                     ~^~~~~~~~~~~

• 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: 0 / 9
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• Subtask 14: 0 / 9