제출 #1364267

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1364267		kai	Tracks in the Snow (BOI13_tracks)	C++20	100 / 100	1158 ms	308724 KiB

tracks

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

#define el '\n'
#define all(x) begin(x), end(x)
#define sz(s) (int)(s.size())

const int N = 4000 + 36;

int h, w;
char a[N][N];
int root[N][N];

int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, 1, 0, -1};

void Solve() {
    cin >> h >> w;

    for(int i = 1; i <= h; i++) {
        for(int j = 1; j <= w; j++) {
            cin >> a[i][j];
        }
    }

    int comp = 1;

    for(int i = 1; i <= h; i++) {
        for(int j = 1; j <= w; j++) {
            if(root[i][j] || a[i][j] == '.') continue;

            queue<pair<int, int>> q;
            q.push({i, j});
            root[i][j] = comp;

            while(!q.empty()) {
                auto [x, y] = q.front();
                q.pop();

                for(int k = 0; k < 4; k++) {
                    int nx = x + dx[k];
                    int ny = y + dy[k];

                    if(nx < 1 || nx > h || ny < 1 || ny > w) continue;
                    if(root[nx][ny]) continue;
                    if(a[nx][ny] != a[x][y]) continue;

                    root[nx][ny] = comp;
                    q.push({nx, ny});
                }
            }

            comp++;
        }
    }

    vector<vector<int>> adj(comp);

    for(int i = 1; i <= h; i++) {
        for(int j = 1; j <= w; j++) {
            if(root[i][j] == 0) continue;

            int u = root[i][j];

            for(int k = 0; k < 4; k++) {
                int ni = i + dx[k];
                int nj = j + dy[k];

                if(ni < 1 || ni > h || nj < 1 || nj > w) continue;
                if(root[ni][nj] == 0) continue;

                int v = root[ni][nj];

                if(u != v) {
                    adj[u].push_back(v);
                }
            }
        }
    }

    for(int i = 1; i < comp; i++) {
        sort(all(adj[i]));
        adj[i].erase(unique(all(adj[i])), adj[i].end());
    }

    vector<int> dist(comp, 0);
    queue<int> q;

    int start = root[1][1];

    dist[start] = 1;
    q.push(start);

    while(!q.empty()) {
        int u = q.front();
        q.pop();

        for(int v : adj[u]) {
            if(dist[v]) continue;

            dist[v] = dist[u] + 1;
            q.push(v);
        }
    }

    int ans = 0;

    for(int i = 1; i < comp; i++) {
        ans = max(ans, dist[i]);
    }

    cout << ans << el;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    Solve();
    return 0;
}

• 서브태스크 1: 30 / 30
• 서브태스크 2: 70 / 70