Submission #811974

#	Time	Username	Problem	Language	Result	Execution time	Memory
811974		devariaota	Tracks in the Snow (BOI13_tracks)	C++17	50.52 / 100	756 ms	51872 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second

const int N = 4e3 + 5;
const int dx[] = {1, 0, -1, 0};
const int dy[] = {0, 1, 0, -1};

queue<pair<int, int>> q1, q2;
char a[N][N];
bool vis[N][N];

int main() { 
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int h, w, cnt = 0, ans = 0;
    cin >> h >> w;
    for (int i = 1; i <= h; i++) {
        for (int j = 1; j <= w; j++) {
            cin >> a[i][j];
            if (a[i][j] != '.') cnt++;
        }
    }
    q1.push({1, 1});
    vis[1][1] = 1, cnt--;
    while (cnt > 0) {
        ans++;
        while (!q1.empty()) {
            int x = q1.front().fi, y = q1.front().se;
            q1.pop();
            cnt--;
            for (int i = 0; i < 4; i++) {
                int tx = x + dx[i], ty = y + dy[i];
                if (tx < 1 or ty < 1 or tx > h or ty > w or vis[tx][ty] or a[tx][ty] == '.') continue;
                else if (a[x][y] == a[tx][ty]) vis[tx][ty] = 1, q1.push({tx, ty});
                else vis[tx][ty] = 1, q2.push({tx, ty});
            }
        }
        q1 = q2;
        while (!q2.empty()) q2.pop();
    }
    cout << ans << "\n";
}  

• Subtask 1: 13.333333333333334 / 30
• Subtask 2: 37.1875 / 70