Submission #793050

#	Time	Username	Problem	Language	Result	Execution time	Memory
793050		MODDI	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	566 ms	132488 KiB

tracks

#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define mp make_pair
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<long long, long long> pll;
using namespace std;
int n, m;
vector<string> mat;
bool vis[4001][4001];
int dist[4001][4001], dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
bool in_range(int i, int j){
	if(i >= 0 && j >= 0 && i < n && j < m)	return true;
	return false;
}
int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cin>>n>>m;
	mat.resize(n);
	for(int i = 0; i < n; i++)
		cin>>mat[i];
	
	deque<pii> q;
	q.push_front(mp(0,0));
	int ans = 1;
	dist[0][0] = vis[0][0] = 1;
	while(!q.empty()){
		pii at = q.front();
		q.pop_front();
		ans = max(ans, dist[at.first][at.second]);
		for(int dir = 0; dir < 4; dir++){
			int nx = at.first + dx[dir], ny = at.second + dy[dir];
			if(in_range(nx, ny) && mat[nx][ny] != '.' && !vis[nx][ny]){
				vis[nx][ny] = true;
				dist[nx][ny] = dist[at.first][at.second] + (mat[at.first][at.second] != mat[nx][ny]);
				if(mat[at.first][at.second] != mat[nx][ny])	q.pb(mp(nx,ny));
				else q.push_front(mp(nx,ny));
				//q.push(mp(-dist[nx][ny], mp(nx,ny)));
			}
		}
	}
	cout<<ans<<endl;
}

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