Submission #437652

#	Time	Username	Problem	Language	Result	Execution time	Memory
437652		Pajaraja	Fountain Parks (IOI21_parks)	C++17	100 / 100	696 ms	44124 KiB

parks

#include "parks.h"
#include <bits/stdc++.h>
#define MAXN 200007
using namespace std;
map<pair<int,int>,int> ind;
std::vector<int> u, v, a, b, x, y, nd;
int dsu[MAXN];
int root(int u)
{
    while(dsu[u]!=u)
    {
        dsu[u]=dsu[dsu[u]];
        u=dsu[u];
    }
    return u;
}
void connect(int u,int v)
{
    int a=root(u),b=root(v);
    if(a==b) return;
    dsu[a]=b;
}
bool cmp(int p,int q) {return x[p]+y[p]>x[q]+y[q];}
void addroad(int p,int q)
{
    int x1=x[p],y1=y[p],x2=x[q],y2=y[q];
    u.push_back(p); v.push_back(q);
    connect(p,q);
    if(x1==x2)
    {
        b.push_back((y1+y2)/2);
        if((x1+y1)&2) a.push_back(x1-1);
        else a.push_back(x1+1);
    }
    else
    {
        a.push_back((x1+x2)/2);
        if((x1+y1)&2) b.push_back(y1+1);
        else b.push_back(y1-1);
    }
}
int construct_roads(std::vector<int> X, std::vector<int> Y) {
    int n=X.size(); x=X; y=Y;
    for(int i=0;i<n;i++) {ind[{x[i],y[i]}]=i+1; dsu[i]=i; nd.push_back(i);}
    sort(nd.begin(),nd.end(),cmp);
    for(int i=0;i<n;i++)
    {
        int c=nd[i]; int ea=ind[{x[c]+2,y[c]}]-1,no=ind[{x[c],y[c]+2}]-1;
        if(ea==-1 && no==-1) continue;
        if(ea!=-1 && no==-1) addroad(c,ea);
        if(ea==-1 && no!=-1) addroad(c,no);
        if(ea!=-1 && no!=-1)
        {
            if(root(ea)!=root(no)) {addroad(c,ea); addroad(c,no);}
            else
            {
                if((x[c]+y[c])&2) addroad(c,no);
                else addroad(c,ea);
            }
        }
    }
    if(u.size()!=n-1) return 0;
    build(u, v, a, b);
    return 1;
}

Compilation message (stderr)

parks.cpp: In function 'int construct_roads(std::vector<int>, std::vector<int>)':
parks.cpp:62:16: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   62 |     if(u.size()!=n-1) return 0;
      |        ~~~~~~~~^~~~~

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