Submission #1201805

#	Time	Username	Problem	Language	Result	Execution time	Memory
1201805		waigoon	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	875 ms	208856 KiB

tracks

#include <bits/stdc++.h>
#define int long long
#define pii pair<int, int>
#define tii tuple<int, int, int>
#define f first
#define s second
#define em emplace
#define emb emplace_back
#define ve vector

using namespace std;

const int inf = 1e18;

int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    int n, m;
    cin >> n >> m;
    ve<ve<char>> a(n, ve<char> (m));
    ve<ve<int>> dis(n, ve<int> (m, inf));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> a[i][j];
        }
    }
    if (a[0][0] == '.') { cout << 0; return 0; }
    deque<pii> q;
    q.emb(0, 0);
    dis[0][0] = 1;
    while (!q.empty()) {
        auto [x, y] = q.front();
        q.pop_front();
        int dx[] = {-1, 0, 1, 0};
        int dy[] = {0, -1, 0, 1};
        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            if (nx < 0 || nx >= n || ny < 0 || ny >= m || a[nx][ny] != a[x][y] || dis[nx][ny] <= dis[x][y]) continue;
            dis[nx][ny] = dis[x][y];
            q.emplace_front(nx, ny);
        }
        for (int i = 0; i < 4; i++) {
            int nx = x + dx[i], ny = y + dy[i];
            if (nx < 0 || nx >= n || ny < 0 || ny >= m || a[nx][ny] == '.' || a[nx][ny] == a[x][y] || dis[nx][ny] <= dis[x][y] + 1) continue;
            dis[nx][ny] = dis[x][y] + 1;
            q.emb(nx, ny);
        }
    }
    int mx = 1;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (a[i][j] == '.') continue;
            mx = max(mx, dis[i][j]);
        }
    }
    cout << mx;
}

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