Submission #854113

#	Time	Username	Problem	Language	Result	Execution time	Memory
854113		nhatvpm	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	547 ms	124000 KiB

tracks

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

using ll = long long;

void setIO(string name) {
	freopen((name+".in").c_str(),"r",stdin);
	freopen((name+".out").c_str(),"w",stdout);
}



void solve(){
	int n,m,dx[]={0,0,1,-1},dy[]={1,-1,0,0};
	cin>>n>>m;
	string grid[n];
	for (int i=0;i<n;i++) cin>>grid[i];
	deque<pair<int,int>> q;
	vector<vector<int>> dis(n,vector<int>(m,0));
	dis[0][0]=1;
	int res=0;
	q.push_front({0,0});
	while (!q.empty()){
		int x=q.front().first,y=q.front().second;
		res=max(res,dis[x][y]);
		q.pop_front();
		for (int i=0;i<4;i++){
			int r=x+dx[i],c=y+dy[i];
			if (r>=0&&r<n&&c>=0&&c<m&&grid[r][c]!='.'&&dis[r][c]==0){
				int w=grid[r][c]!=grid[x][y]?1:0;
				
					dis[r][c]=dis[x][y]+w;
					if (w==1) q.push_back({r,c});
					else q.push_front({r,c});
				
				
			}
		}
	}
	cout<<res;
	
	
	
	
	
	
	
}


int main(){
	//setIO("");
	ios_base::sync_with_stdio(0);
    cin.tie(0);
	int tc=1;
	//cin>>tc;
	while (tc--){
		solve();
	}
}

Compilation message (stderr)

tracks.cpp: In function 'void setIO(std::string)':
tracks.cpp:7:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    7 |  freopen((name+".in").c_str(),"r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:8:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    8 |  freopen((name+".out").c_str(),"w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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