Submission #790783

#	Time	Username	Problem	Language	Result	Execution time	Memory
790783		KindaNameless	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	576 ms	130912 KiB

tracks

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

#define ll long long
#define ull unsigned long long
#define ld long double
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define all(a) a.begin(), a.end()

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

char M[4001][4001];
int dist[4001][4001];

int main(){
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int H, W; cin >> H >> W;

    for(int i = 1; i <= H; ++i){
        for(int j = 1; j <= W; ++j){
            cin >> M[i][j];
            dist[i][j] = 1e9;
        }
    }

    deque<pair<int, int>> dq;
    dq.push_front({1, 1});
    dist[1][1] = 1;

    int answer = 1;
    while(!dq.empty()){
        int x, y; tie(x, y) = dq.front(); dq.pop_front();

        for(int k = 0; k < 4; ++k){
            int nx = x + dx[k], ny = y + dy[k];
            if(nx > 0 && ny > 0 && nx <= H && ny <= W && dist[nx][ny] == 1e9 && M[nx][ny] != '.'){
                dist[nx][ny] = dist[x][y];
                if(M[x][y] != M[nx][ny]){
                    dist[nx][ny]++;
                    dq.push_back({nx, ny});
                }
                else{
                    dq.push_front({nx, ny});
                }
                answer = max(answer, dist[nx][ny]);
            }
        }
    }

    cout << answer;

    return 0;
}

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