Submission #1135443

#	Time	Username	Problem	Language	Result	Execution time	Memory
1135443		neowami	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	631 ms	119020 KiB

tracks

#include <bits/stdc++.h> // NeOWami
using namespace std;

#define ft first
#define sc second
using pii = pair<int, int>;
const int N = 4005;
const int inf = 1e9;
int n, m, ans = 0;
char c[N][N];
int dist[N][N];
int Dx[] = {1, -1, 0, 0}, Dy[] = {0, 0, -1, 1};
bool ckmin(int &u, int v) {
    if (u > v) return u = v, 1;
    return 0;
}
signed main() {
    cin.tie(NULL)->sync_with_stdio(false);
    if(ifstream("Input.inp")) {
        freopen("Input.inp", "r", stdin);
        freopen("Output.out", "w", stdout);
    }
    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            cin >> c[i][j];
            dist[i][j] = inf;
        }
    }
    dist[1][1] = 1;
    deque<pii> dq;
    dq.push_back({1, 1});
    while(!dq.empty()) {
        int x = dq.back().ft, y = dq.back().sc;
        dq.pop_back();
        ans = max(ans, dist[x][y]);

        for (int mov = 0; mov < 4; mov++) {
            int tx = x + Dx[mov], ty = y + Dy[mov];
            if (!tx || !ty || tx > n || ty > m || c[tx][ty] == '.') continue;
            if (c[tx][ty] == c[x][y] && ckmin(dist[tx][ty], dist[x][y])) dq.push_back({tx, ty});
            if (c[tx][ty] != c[x][y] && ckmin(dist[tx][ty], dist[x][y] + 1)) dq.push_front({tx, ty});
        }
    }
    cout << ans;
    return 0;
}

Compilation message (stderr)

tracks.cpp: In function 'int main()':
tracks.cpp:20:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   20 |         freopen("Input.inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:21:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   21 |         freopen("Output.out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

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