Submission #1132404

#	Time	Username	Problem	Language	Result	Execution time	Memory
1132404		henriess	The Kingdom of JOIOI (JOI17_joioi)	C++20	0 / 100	0 ms	324 KiB

joioi

#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <climits>

using namespace std;

int H, W;
vector<vector<int>> altitude;

// Directions for moving in the grid (up, down, left, right)
const int dx[] = {-1, 1, 0, 0};
const int dy[] = {0, 0, -1, 1};

bool is_valid(int x, int y) {
    return x >= 0 && x < H && y >= 0 && y < W;
}

// Check if it's possible to divide the grid with the given maximum altitude difference
bool can_divide(int T) {
    vector<vector<bool>> visited(H, vector<bool>(W, false));

    auto bfs = [&](int sx, int sy, int region) {
        queue<pair<int, int>> q;
        q.emplace(sx, sy);
        visited[sx][sy] = true;

        vector<pair<int, int>> cells;

        while (!q.empty()) {
            auto [x, y] = q.front();
            q.pop();
            cells.emplace_back(x, y);

            for (int d = 0; d < 4; ++d) {
                int nx = x + dx[d];
                int ny = y + dy[d];
                if (is_valid(nx, ny) && !visited[nx][ny] && abs(altitude[x][y] - altitude[nx][ny]) <= T) {
                    visited[nx][ny] = true;
                    q.emplace(nx, ny);
                }
            }
        }

        return cells;
    };

    vector<vector<pair<int, int>>> regions;

    for (int i = 0; i < H; ++i) {
        for (int j = 0; j < W; ++j) {
            if (!visited[i][j]) {
                regions.push_back(bfs(i, j, regions.size()));
            }
        }
    }

    return regions.size() == 2;
}

int main() {
    cin >> H >> W;
    altitude.resize(H, vector<int>(W));

    int min_alt = INT_MAX, max_alt = INT_MIN;
    for (int i = 0; i < H; ++i) {
        for (int j = 0; j < W; ++j) {
            cin >> altitude[i][j];
            min_alt = min(min_alt, altitude[i][j]);
            max_alt = max(max_alt, altitude[i][j]);
        }
    }

    int left = 0, right = max_alt - min_alt;
    int result = right;

    while (left <= right) {
        int mid = left + (right - left) / 2;

        if (can_divide(mid)) {
            result = mid;
            right = mid - 1;
        } else {
            left = mid + 1;
        }
    }

    cout << result << endl;
    return 0;
}

• Subtask 1: 0 / 15
• Subtask 2: 0 / 45
• Subtask 3: 0 / 40