제출 #445398

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
445398		apostoldaniel854	분수 공원 (IOI21_parks)	C++17	100 / 100	686 ms	56712 KiB

parks

#include "parks.h"

#include <map>
#include <algorithm>
#include <iostream>
const int MAX_N = 2e5;

int dx[] = {0, 0, -1, 1};
int dy[] = {-1, 1, 0, 0};
int dxb[] = {-1, -1, 1, 1};
int dyb[] = {-1, 1, -1, 1};
bool used[1 + MAX_N];
std::map <std::pair <int, int>, int> fountains;
int nr;
void dfs (int node, std::vector <int> &x, std::vector <int> &y) {
    used[node] = true;
    ++nr;
    for (int dir = 0; dir < 4; dir++) {
        int nx = x[node] + 2 * dx[dir];
        int ny = y[node] + 2 * dy[dir];
        if (fountains.count ({nx, ny})) {
            int vec = fountains[{nx, ny}];
            if (not used[vec])
                dfs (vec, x, y);
        }

    }
}

int construct_roads(std::vector<int> x, std::vector<int> y) {
    std::vector<int> u, v, a, b;
    int n = x.size ();
    std::vector <std::pair <int, int>> bitches;
    for (int i = 0; i < n; i++) {
        fountains[{x[i], y[i]}] = i;
        for (int dir = 0; dir < 4; dir++) {
            int nx = x[i] + dxb[dir];
            int ny = y[i] + dyb[dir];
            bitches.push_back ({nx, ny});
        }
    }
    nr = 0;
    dfs (0, x, y);
    if (nr < n)
        return 0;
    sort (bitches.begin (), bitches.end ());
    bitches.resize (std::unique (bitches.begin (), bitches.end ()) - bitches.begin ());
    for (std::pair <int, int> p : bitches) {
        int color = (p.first / 2 + p.second / 2) % 2;
        if (color == 0) {
            /// <- or -> orizontal road

            /// case 1 try from above
            if (fountains.count({p.first - 1, p.second - 1}) && fountains.count ({p.first - 1, p.second + 1})) {
                u.push_back (fountains[{p.first - 1, p.second - 1}]);
                v.push_back (fountains[{p.first - 1, p.second + 1}]);
                a.push_back (p.first);
                b.push_back (p.second);
            }
            /// case 2 try from below
            else if (fountains.count ({p.first + 1, p.second - 1}) && fountains.count ({p.first + 1, p.second + 1})) {
                u.push_back (fountains[{p.first + 1, p.second - 1}]);
                v.push_back (fountains[{p.first + 1, p.second + 1}]);
                a.push_back (p.first);
                b.push_back (p.second);
            }
        }
        else {
            /// v or ^ vertical road

            /// case 1 try from the LHS
            if (fountains.count({p.first - 1, p.second - 1}) && fountains.count ({p.first + 1, p.second - 1})) {
                u.push_back (fountains[{p.first - 1, p.second - 1}]);
                v.push_back (fountains[{p.first + 1, p.second - 1}]);
                a.push_back (p.first);
                b.push_back (p.second);
            }
            /// case 2 try from the RHS
            else if (fountains.count ({p.first - 1, p.second + 1}) && fountains.count ({p.first + 1, p.second + 1})) {
                u.push_back (fountains[{p.first - 1, p.second + 1}]);
                v.push_back (fountains[{p.first + 1, p.second + 1}]);
                a.push_back (p.first);
                b.push_back (p.second);
            }
        }
    }
    build(u, v, a, b);
    return 1;
}
/**
5
4 4
4 6
6 4
4 2
2 4

**/

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