Submission #962615

#	Time	Username	Problem	Language	Result	Execution time	Memory
962615		novus677	Tracks in the Snow (BOI13_tracks)	C++17	89.06 / 100	2070 ms	58192 KiB

tracks

#include <iostream>
#include <queue>
#include <tuple>

using namespace std;

int H, W;
char grid[4000][4000];
bool visited[4000][4000];

int main() {
    cin >> H >> W;

    for (int i = 0; i < H; ++i) {
        string row;
        cin >> row;
        for (int j = 0; j < W; ++j) {
            grid[i][j] = row[j];
        }
    }

    int answer = 1;
    priority_queue<tuple<int, int, int>> queue;
    queue.push({-1, 0, 0});
    visited[0][0] = true;
    while (!queue.empty()) {
        auto [marker, i, j] = queue.top();
        queue.pop();
        answer = max(answer, -marker);

        if (i > 0 && !visited[i - 1][j]) {
            if (grid[i - 1][j] == grid[i][j]) {
                visited[i - 1][j] = true;
                queue.push({marker, i - 1, j});
            } else if (grid[i - 1][j] != '.') {
                visited[i - 1][j] = true;
                queue.push({marker - 1, i - 1, j});
            }
        }
        if (i < H - 1 && !visited[i + 1][j]) {
            if (grid[i + 1][j] == grid[i][j]) {
                visited[i + 1][j] = true;
                queue.push({marker, i + 1, j});
            } else if (grid[i + 1][j] != '.') {
                visited[i + 1][j] = true;
                queue.push({marker - 1, i + 1, j});
            }
        }
        if (j > 0 && !visited[i][j - 1]) {
            if (grid[i][j - 1] == grid[i][j]) {
                visited[i][j - 1] = true;
                queue.push({marker, i, j - 1});
            } else if (grid[i][j - 1] != '.') {
                visited[i][j - 1] = true;
                queue.push({marker - 1, i, j - 1});
            }
        }
        if (j < W - 1 && !visited[i][j + 1]) {
            if (grid[i][j + 1] == grid[i][j]) {
                visited[i][j + 1] = true;
                queue.push({marker, i, j + 1});
            } else if (grid[i][j + 1] != '.') {
                visited[i][j + 1] = true;
                queue.push({marker - 1, i, j + 1});
            }
        }
    }

    cout << answer << '\n';
}

• Subtask 1: 30 / 30
• Subtask 2: 59.0625 / 70