Submission #451963

#	Time	Username	Problem	Language	Result	Execution time	Memory
451963		vector	Fountain Parks (IOI21_parks)	C++17	100 / 100	845 ms	49188 KiB

parks

#include "parks.h"
#include <bits/stdc++.h>
#define SIZE 200001
using namespace std;
struct point
{
    int x, y, idx;
};
set<pair<int, int> > vis;
map<pair<int, int>, int> fnt;
point p[SIZE];
int root[SIZE], cnt;
int dx[5][3]=
{
    { 1, 1 },
    { 1, -1 },
    { -1, 1 },
    { -1, -1 }
};
int Find(int x)
{
    if (x==root[x]) return x;
    return root[x]=Find(root[x]);
}
void Union(int x, int y)
{
    if (Find(x)==Find(y)) return;
    root[root[y]]=root[x], cnt++;
}
bool comp1(point a, point b)
{
    if (a.x==b.x) return a.y<b.y;
    return a.x<b.x;
}
bool comp2(point a, point b)
{
    if (a.y==b.y) return a.x<b.x;
    return a.y<b.y;
}
int construct_roads(vector<int> X, vector<int> Y)
{
    int N=X.size();
    for (int i=0; i<N; i++) {
        p[i].x=X[i], p[i].y=Y[i], p[i].idx=i, root[i]=i;
        fnt.insert({{X[i], Y[i]}, i});
    }
    sort(p, p+N, comp1);
    for (int i=0; i<N-1; i++) if (p[i].x==p[i+1].x && p[i].y==p[i+1].y-2) Union(p[i].idx, p[i+1].idx);
    sort(p, p+N, comp2);
    for (int i=0; i<N-1; i++) if (p[i].y==p[i+1].y && p[i].x==p[i+1].x-2) Union(p[i].idx, p[i+1].idx);
    if (cnt!=N-1) return 0;

    int bx, by;
    vector<int> u, v, a, b;
    for (int i=0; i<N; i++) for (int j=0; j<4; j++) {
        bx=p[i].x+dx[j][0], by=p[i].y+dx[j][1];
        if (vis.find({bx, by})==vis.end()) {
            vis.insert({bx, by});
            if ((bx+by)%4==0) {
                if (fnt.find({bx-1, by-1})!=fnt.end() && fnt.find({bx-1, by+1})!=fnt.end()) u.push_back(fnt[{bx-1, by-1}]), v.push_back(fnt[{bx-1, by+1}]), a.push_back(bx), b.push_back(by);
                else if (fnt.find({bx+1, by-1})!=fnt.end() && fnt.find({bx+1, by+1})!=fnt.end()) u.push_back(fnt[{bx+1, by-1}]), v.push_back(fnt[{bx+1, by+1}]), a.push_back(bx), b.push_back(by);
            }
            else {
                if (fnt.find({bx-1, by-1})!=fnt.end() && fnt.find({bx+1, by-1})!=fnt.end()) u.push_back(fnt[{bx-1, by-1}]), v.push_back(fnt[{bx+1, by-1}]), a.push_back(bx), b.push_back(by);
                else if (fnt.find({bx-1, by+1})!=fnt.end() && fnt.find({bx+1, by+1})!=fnt.end()) u.push_back(fnt[{bx-1, by+1}]), v.push_back(fnt[{bx+1, by+1}]), a.push_back(bx), b.push_back(by);
            }
        }
    }
    build(u, v, a, b);
    return 1;
}

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