Submission #788482

#	Time	Username	Problem	Language	Result	Execution time	Memory
788482		alexander707070	Fountain Parks (IOI21_parks)	C++17	55 / 100	1444 ms	181520 KiB

parks

#include<bits/stdc++.h>
#include "parks.h"
#define MAXN 800007
using namespace std;

struct bench{
    int from,to;
    int a,b;
};

int n,curr,benches,br,k,comp[MAXN],ans[MAXN],dsu[MAXN];
bool li[MAXN];
vector<int> v[MAXN],r[MAXN];
stack<int> st;

vector<bench> sol;
vector<int> A,B,C,D;
vector< pair<int,int> > ors;

map< pair<int,int>, int> mp;
map< pair<int,int>, vector<int> > bro;

int op(int x){
    if(x<400000)return x+400000;
    return x-400000;
}

void add(int x,int y,int z){
    for(int i=0;i<bro[{x,y}].size();i++){
        ors.push_back({op(bro[{x,y}][i]),op(z)});
    }
    bro[{x,y}].push_back(z);
}

void dfs(int x){
    li[x]=true;
    for(int i=0;i<v[x].size();i++){
        if(!li[v[x][i]])dfs(v[x][i]);
    }
    st.push(x);
}

void scc(int x){
    comp[x]=k;
    li[x]=true;

    for(int i=0;i<r[x].size();i++){
        if(!li[r[x][i]])scc(r[x][i]);
    }
}

int root(int x){
    if(dsu[x]==x)return x;
    dsu[x]=root(dsu[x]);
    return dsu[x];
}

void mergev(int x,int y){
    dsu[root(x)]=root(y);
}

int construct_roads(vector<int> x,vector<int> y){
    n=int(x.size());

    for(int i=0;i<n;i++){
        dsu[i]=i;
        mp[{x[i],y[i]}]=i+1;
    }

    br=0;
    for(int i=0;i<n;i++){
        curr=mp[{x[i]-2,y[i]}];
        if(curr!=0 and root(i)!=root(curr-1)){
            curr--; mergev(i,curr);

            add(x[i]-1,y[i]-1,br);
            add(x[i]-1,y[i]+1,br+1);
            ors.push_back({br,br+1});
            
            br+=2;
        }

        curr=mp[{x[i],y[i]-2}];
        if(curr!=0 and root(i)!=root(curr-1)){
            curr--; mergev(i,curr);

            add(x[i]-1,y[i]-1,br);
            add(x[i]+1,y[i]-1,br+1);
            ors.push_back({br,br+1});

            br+=2;
        }
    }

    if(br!=2*n-2)return 0;

    for(int i=0;i<ors.size();i++){
        v[op(ors[i].first)].push_back(ors[i].second);
        r[ors[i].second].push_back(op(ors[i].first));

        v[op(ors[i].second)].push_back(ors[i].first);
        r[ors[i].first].push_back(op(ors[i].second));
    }

    for(int i=0;i<800000;i++){
        if(!li[i])dfs(i);
    }
    for(int i=0;i<800000;i++)li[i]=false;
    while(!st.empty()){
        if(!li[st.top()]){
            k++; scc(st.top());
        }
        st.pop();
    }

    for(int i=0;i<br;i++){
        if(comp[i]==comp[op(i)])return 0;
        if(comp[i]<comp[op(i)])ans[i]=0;
        else ans[i]=1;
    }

    for(int i=0;i<n;i++)dsu[i]=i;

    br=0;
    for(int i=0;i<n;i++){
        curr=mp[{x[i]-2,y[i]}];
        if(curr!=0 and root(i)!=root(curr-1)){
            curr--; mergev(i,curr);
        
            if(ans[br]==0 and ans[br+1]==0)return -1;
            if(ans[br]==1){
                sol.push_back({curr,i,x[i]-1,y[i]-1});
            }else{
                sol.push_back({curr,i,x[i]-1,y[i]+1});
            }
            
            br+=2;
        }

        curr=mp[{x[i],y[i]-2}];
        if(curr!=0 and root(i)!=root(curr-1)){
            curr--; mergev(i,curr);

            if(ans[br]==0 and ans[br+1]==0)return -1;
            if(ans[br]==1){
                sol.push_back({curr,i,x[i]-1,y[i]-1});
            }else{
                sol.push_back({curr,i,x[i]+1,y[i]-1});
            }

            br+=2;
        }
    }
    
    for(int i=0;i<sol.size();i++){
        A.push_back(sol[i].from);
        B.push_back(sol[i].to);
        C.push_back(sol[i].a);
        D.push_back(sol[i].b);
    }

    build(A,B,C,D);
    return 1;
}

/*
int main(){
    cout<<construct_roads({4, 4, 6, 4, 2}, {4, 6, 4, 2, 4});
}
*/

Compilation message (stderr)

parks.cpp: In function 'void add(int, int, int)':
parks.cpp:29:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |     for(int i=0;i<bro[{x,y}].size();i++){
      |                 ~^~~~~~~~~~~~~~~~~~
parks.cpp: In function 'void dfs(int)':
parks.cpp:37:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   37 |     for(int i=0;i<v[x].size();i++){
      |                 ~^~~~~~~~~~~~
parks.cpp: In function 'void scc(int)':
parks.cpp:47:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |     for(int i=0;i<r[x].size();i++){
      |                 ~^~~~~~~~~~~~
parks.cpp: In function 'int construct_roads(std::vector<int>, std::vector<int>)':
parks.cpp:97:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   97 |     for(int i=0;i<ors.size();i++){
      |                 ~^~~~~~~~~~~
parks.cpp:155:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<bench>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  155 |     for(int i=0;i<sol.size();i++){
      |                 ~^~~~~~~~~~~

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