Submission #1101238

#	Time	Username	Problem	Language	Result	Execution time	Memory
1101238		JohnnyVenturas	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	1555 ms	445712 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
int rows[]{1, -1, 0, 0};
int cols[]{0, 0, 1, -1};

struct inf {
    int r, c, d;
    inf() {}
    inf(int r, int c, int d) : r(r), c(c), d(d) {}
};

void bfs(vector<vector<char>> &grid, vector<vector<int>> &distances) {
    deque<inf> dq;
    dq.push_front(inf(0, 0, 1));

    while (!dq.empty()) {
        auto top = dq.front();
        dq.pop_front();

        if (distances[top.r][top.c] != 1e9)
            continue;

        distances[top.r][top.c] = top.d;

        for (int i = 0; i < 4; ++i) {
            int nrow = top.r + rows[i];
            int ncol = top.c + cols[i];
            if (nrow < 0 || ncol < 0 || nrow == grid.size() ||
                ncol == grid[0].size())
                continue;
            if (grid[nrow][ncol] == '.')
                continue;
            if (grid[nrow][ncol] != grid[top.r][top.c]) {
                dq.push_back(inf(nrow, ncol, top.d + 1));
            } else {
                dq.push_front(inf(nrow, ncol, top.d));
            }
        }
    }
}

int main() {
    int n, m;
    cin >> n >> m;

    vector<vector<char>> grid(n, vector<char>(m, '.'));

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            cin >> grid[i][j];
        }
    }

    vector<vector<int>> distances(n, vector<int>(m, 1e9));

    bfs(grid, distances);

    int max_value = 0;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
                                                if(grid[i][j] == '.') continue;
            max_value = max(max_value, distances[i][j]);
        }
    }
    cout << max_value << "\n";
}

Compilation message (stderr)

tracks.cpp: In function 'void bfs(std::vector<std::vector<char> >&, std::vector<std::vector<int> >&)':
tracks.cpp:28:46: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::vector<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |             if (nrow < 0 || ncol < 0 || nrow == grid.size() ||
      |                                         ~~~~~^~~~~~~~~~~~~~
tracks.cpp:29:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |                 ncol == grid[0].size())
      |                 ~~~~~^~~~~~~~~~~~~~~~~

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