Submission #1048097

#	Time	Username	Problem	Language	Result	Execution time	Memory
1048097		vjudge1	Fountain Parks (IOI21_parks)	C++17	5 / 100	319 ms	79532 KiB

parks

#include "parks.h"
#include<bits/stdc++.h>
using namespace std;
mt19937 rng;
struct bpmatch{
    vector<int>adj[200100];
    int match1[200100],match2[400100],dep[200100];
    void AE(int a,int b){
        adj[a].push_back(b);
    }
    int bfs(int n){
        queue<int>q;
        for(int i=1;i<=n;i++)
            if(!match1[i])
                q.push(i),
                dep[i]=1;
            else dep[i]=0;
        dep[0]=0;
        while(q.size()){
            int x=q.front();
            q.pop();
            if(dep[x]>=dep[0]&&dep[0])
                continue;
            for(auto i:adj[x])
                if(!dep[match2[i]])
                    dep[match2[i]]=dep[x]+1,
                    q.push(match2[i]);
        }
        return dep[0];
    }
    int dfs(int n){
        if(!n)return 1;
        for(auto i:adj[n]){
            if(dep[match2[i]]==dep[n]+1&&dfs(match2[i]))
                return match2[match1[n]=i]=n,1;
        }
        dep[n]=1e9;
        return 0;
    }
    int matching(int n){
        int ans=0;
        while(bfs(n))for(int i=1;i<=n;i++)
            if(!match1[i]) ans+=dfs(i);
        return ans;
    }
} G;
map<int,int> pts[200100];
vector<pair<int,int>> tre_edges;
struct dsu{
    int par[200100];
    int abp(int n){
        return par[n]?par[n]=abp(par[n]):n;
    }
    int  merge(int a,int b){
        a=abp(a),b=abp(b);
        return a-b?par[a]=b:0;
    }
} DT;
int Xpos[400100],Ypos[400100];
int construct_roads(std::vector<int> x, std::vector<int> y) {
    int n=x.size();
    for(int i=0;i<n;i++)
        pts[x[i]][y[i]]=i+1;
    vector<tuple<int,int,int>>E;
    for(int i=0;i<n;i++) {
        if(pts[x[i]+2][y[i]])
            E.push_back({i+1,pts[x[i]+2][y[i]],0});
        if(pts[x[i]][y[i]+2])
            E.push_back({i+1,pts[x[i]][y[i]+2],1});
    }
    vector<int>u,v,A,B;
    shuffle(E.begin(),E.end(),rng);
    int CC=0;
    for(auto [i,j,k]:E){
        if(DT.merge(i,j)){
            u.push_back(i-1);
            v.push_back(j-1);
            int x1=x[i-1]+1,y1=y[i-1]+1;
            int x2=x1,y2=y1;
            if(j)x2-=2;
            else y2-=2;
            if(!pts[x1][y1])
                pts[x1][y1]=++CC,
                Xpos[CC]=x1,
                Ypos[CC]=y1;
            if(!pts[x2][y2])
                pts[x2][y2]=++CC,
                Xpos[CC]=x2,
                Ypos[CC]=y2;
            G.AE(u.size(),pts[x1][y1]);
            G.AE(u.size(),pts[x2][y2]);
        }
    }
    if(u.size()-n+1)return 0;
    assert(G.matching(n-1)==n-1);
    for(int i=1;i<n;i++)
        A.push_back(Xpos[G.match1[i]]),
        B.push_back(Ypos[G.match1[i]]);
    build(u,v,A,B);
    return 1;
}

• Subtask 1: 5 / 5
• Subtask 2: 0 / 10
• Subtask 3: 0 / 15
• Subtask 4: 0 / 20
• Subtask 5: 0 / 20
• Subtask 6: 0 / 30