Submission #1022426

#	Time	Username	Problem	Language	Result	Execution time	Memory
1022426		mdn2002	Fountain Parks (IOI21_parks)	C++17	100 / 100	1417 ms	91756 KiB

parks

/*
Mayoeba Yabureru
*/
#include "parks.h"
#include<bits/stdc++.h>
using namespace std;
static vector<int> _u, _v, _a, _b;

int construct_roads(vector<int> x, vector<int> y) {
    int n = x.size();
    vector<vector<int>> gr(n + 1);
    vector<int> dsu(n + 1);
    map<pair<int, int>, int> mp;
    map<pair<int, int>, pair<int, int>> mpp;
    vector<pair<int, int>> vv;
    x.insert(x.begin(), 0);
    y.insert(y.begin(), 0);
    for (int i = 1; i <= n; i ++) {
        mp[{x[i], y[i]}] = i;
        vv.push_back({x[i], y[i]});
        dsu[i] = i;
    }
    vector<int> u, v, a, b;
    map<pair<int, int>, int> taken;

    function<int(int)> fp = [&](int x) {
        if (dsu[x] == x) return x;
        return dsu[x] = fp(dsu[x]);
    };

    function cmp = [&] (pair<int, int> a, pair<int, int> b) {
        if (a.first + a.second < b.first + b.second) return 1;
        return 0;
    };
    sort(vv.begin(), vv.end(), cmp);
    for (int i = 0; i < n; i ++) {
        auto xx = make_pair(vv[i].first, vv[i].second - 2);
        int fx = fp(mp[vv[i]]), fy = fp(mp[xx]);
        if (mp[xx] && fx != fy) {
            int ad = (vv[i].first + vv[i].second) % 4;
            if (taken[{vv[i].first - 1 + ad, vv[i].second - 1}] == 0) {
                mpp[{mp[vv[i]], mp[xx]}] = {vv[i].first - 1 + ad, vv[i].second - 1};
                taken[{vv[i].first - 1 + ad, vv[i].second - 1}] = 1;
                u.push_back(mp[vv[i]]);
                v.push_back(mp[xx]);
                gr[mp[vv[i]]].push_back(mp[xx]);
                gr[mp[xx]].push_back(mp[vv[i]]);
                dsu[fx] = fy;
            }
        }
        xx = make_pair(vv[i].first - 2, vv[i].second);
        fx = fp(mp[vv[i]]), fy = fp(mp[xx]);
        if (mp[xx] && fx != fy) {
            int ad = (vv[i].first + vv[i].second) % 4;
            if (taken[{vv[i].first - 1, vv[i].second + 1 - ad}] == 0) {
                mpp[{mp[vv[i]], mp[xx]}] = {vv[i].first - 1, vv[i].second + 1 - ad};
                taken[{vv[i].first - 1, vv[i].second + 1 - ad}] = 1;
                u.push_back(mp[vv[i]]);
                v.push_back(mp[xx]);
                gr[mp[vv[i]]].push_back(mp[xx]);
                gr[mp[xx]].push_back(mp[vv[i]]);
                dsu[fx] = fy;
            }
        }
    }

    int num = 0, st = 1;
    vector<int> vis(n + 1);

    function<void(int)> go = [&] (int v) {
        num ++;
        vis[v] = 1;
        for (auto u : gr[v]) {
            if (vis[u] == 0) go(u);
        }
    };
    go(st);
    for (int i = 0; i < u.size(); i ++) {
        a.push_back(mpp[{u[i], v[i]}].first);
        b.push_back(mpp[{u[i], v[i]}].second);
        u[i] --;
        v[i] --;
    }
    if (num == n) {
        build(u, v, a, b);
        return 1;
    }
    return 0;
}

Compilation message (stderr)

parks.cpp: In function 'int construct_roads(std::vector<int>, std::vector<int>)':
parks.cpp:78:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |     for (int i = 0; i < u.size(); 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