Submission #491684

#	Time	Username	Problem	Language	Result	Execution time	Memory
491684		MeGustaElArroz23	Fountain Parks (IOI21_parks)	C++17	100 / 100	782 ms	94420 KiB

parks

#include "parks.h"

#include<bits/stdc++.h>

using namespace std;

#define vi vector<int>
#define pii pair<int,int>
#define vii vector<pii>
#define fi first
#define se second

class dsu{
    public:
    vi ind;
    vi size;

    dsu(int n){
        ind=vi(n);
        for (int i=0;i<n;i++) ind[i]=i;
        size=vi(n,1);
    }

    int find(int x){
        if (ind[x]==x) return x;
        ind[x]=find(ind[x]);
        return ind[x];
    }

    void unite(int a, int b){
        a=find(a);
        b=find(b);
        if (a==b) return;
        if (size[a]<size[b]) swap(a,b);
        size[a]+=size[b];
        ind[b]=a;
    }
};

int construct_roads(vi cordx, vi cordy){
    int n=cordx.size();
    vii v(n);
    for (int i=0;i<n;i++) v[i]=pii{cordx[i],cordy[i]};

    vi u; //ind fuentes
    vi w;
    vi a; // coord banco
    vi b;

    map<pii,int> indfuente;
    for (int i=0;i<n;i++) indfuente[v[i]]=i+1;

    set<pii> posiblesbancos;
    for (pii p:v){
        posiblesbancos.insert(pii{p.fi+1,p.se+1});
        posiblesbancos.insert(pii{p.fi+1,p.se-1});
        posiblesbancos.insert(pii{p.fi-1,p.se+1});
        posiblesbancos.insert(pii{p.fi-1,p.se-1});
    }

    for (pii p:posiblesbancos){
        if ((p.fi+p.se)%4==0){
            if (indfuente[pii{p.fi+1,p.se+1}] && indfuente[pii{p.fi-1,p.se+1}]){
                u.push_back(indfuente[pii{p.fi+1,p.se+1}]-1);
                w.push_back(indfuente[pii{p.fi-1,p.se+1}]-1);
                a.push_back(p.fi);
                b.push_back(p.se);
            }
            else if (indfuente[pii{p.fi+1,p.se-1}] && indfuente[pii{p.fi-1,p.se-1}]){
                u.push_back(indfuente[pii{p.fi+1,p.se-1}]-1);
                w.push_back(indfuente[pii{p.fi-1,p.se-1}]-1);
                a.push_back(p.fi);
                b.push_back(p.se);
            }
        }
        else{
            if (indfuente[pii{p.fi+1,p.se+1}] && indfuente[pii{p.fi+1,p.se-1}]){
                u.push_back(indfuente[pii{p.fi+1,p.se+1}]-1);
                w.push_back(indfuente[pii{p.fi+1,p.se-1}]-1);
                a.push_back(p.fi);
                b.push_back(p.se);
            }
            else if (indfuente[pii{p.fi-1,p.se+1}] && indfuente[pii{p.fi-1,p.se-1}]){
                u.push_back(indfuente[pii{p.fi-1,p.se+1}]-1);
                w.push_back(indfuente[pii{p.fi-1,p.se-1}]-1);
                a.push_back(p.fi);
                b.push_back(p.se);
            }
        }
    }

    dsu comp(n);
    for (int i=0;i<u.size();i++) comp.unite(u[i],w[i]);

    for (int i=0;i<n;i++) if (comp.find(i)!=comp.find(0)) return 0;

    build(u,w,a,b);
 
    return 1;
}

Compilation message (stderr)

parks.cpp: In function 'int construct_roads(std::vector<int>, std::vector<int>)':
parks.cpp:94:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |     for (int i=0;i<u.size();i++) comp.unite(u[i],w[i]);
      |                  ~^~~~~~~~~

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