Submission #1000181

#	Time	Username	Problem	Language	Result	Execution time	Memory
1000181		a5a7	Tracks in the Snow (BOI13_tracks)	C++14	2.19 / 100	311 ms	219732 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template <class T> 
using indexedset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long ll;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, m;
    cin >> n >> m;
    char grid[n][m];
    ll dist[n][m];
    int visited[n][m];
    for (int i = 0; i < n; i++){
        for (int j = 0; j < m; j++){
            cin >> grid[i][j];
            dist[i][j] = 1e18;
            visited[i][j] = 0;
        }
    }
    deque<pair<int, int>> q;
    dist[0][0] = 0;
    q.push_back({0, 0});
    vector<pair<int, int>> dir = {{-1, 0}, {1, 0}, {0, 1}, {0, -1}};
    while (!q.empty()){
        auto x = q.front();
        q.pop_back();
        if (visited[x.first][x.second]) continue;
        visited[x.first][x.second] = 1;
        for (auto y : dir){
            int nx = x.first + y.first;
            int ny = x.second + y.second;
            if (nx < 0 || ny < 0 || nx >= n || ny >= m) continue;
            if (grid[nx][ny] == '.') continue;
            int d = grid[nx][ny] == grid[x.first][x.second] ? 0 : 1;
            if (dist[nx][ny] > (d+dist[x.first][x.second])){
                dist[nx][ny] = d+dist[x.first][x.second];
                if (d == 0){
                    q.push_front({nx, ny});
                }else{
                    q.push_back({nx, ny});
                }
            }
        }
    }
    ll ans = 0;
    for (int i = 0; i < n; i++){
        for (int j = 0; j < m; j++){
            if (dist[i][j] == 1e18) continue;
            ans = max(ans, dist[i][j]);
        }
    }
    cout << (ans+1) << endl;
}

• Subtask 1: 0 / 30
• Subtask 2: 2.1875 / 70