Submission #591323

#	Time	Username	Problem	Language	Result	Execution time	Memory
591323		imObscure	Tracks in the Snow (BOI13_tracks)	C++17	100 / 100	955 ms	222124 KiB

tracks

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


using vi = vector<int>;
#define pb push_back
#define all(x) begin(x), end(x)
#define sz(x) (int) (x).size()

using pi = pair<int,int>;
#define f first
#define s second
#define mp make_pair

#define re(i,n) for(int i=0;i<n;i++)
#define reb(i,n) for(int i=n-1;i>=0;i--)
#define test int t;cin>>t;while(t--)


void setIO(string name = "") {
	cin.tie(0)->sync_with_stdio(0); 
	if (sz(name)) {
		freopen((name + ".in").c_str(), "r", stdin); 
		freopen((name + ".out").c_str(), "w", stdout);
	}
}

signed main(){
	setIO();
	
	int n,m; cin>>n>>m;
	
	vector<string> grid(n);
	vector<vi> vis(n,vi(m));
	re(i,n)cin>>grid[i];
	
	deque<pair<int,pair<int,int>>> q;
	q.pb({1,{0,0}});
	
	int r[4]={1,-1,0,0};
	int c[4]={0,0,-1,1};
	int ans=0;
	
	while(sz(q)){
		
		pair<int,pair<int,int>> cur=q.front(); q.pop_front();
		
		
			ans=max(ans,cur.f);
			
		
		vis[cur.s.f][cur.s.s]=1;
		
		for(int i=0;i<4;i++){
			
			int x=cur.s.f+r[i],y=cur.s.s+c[i];
			
			if(x>=0 && x<n && y>=0 && y<m && !vis[x][y] && grid[x][y]!='.'){
				if(grid[x][y]!=grid[cur.s.f][cur.s.s]){
					q.push_back({cur.f+1,{x,y}});
				}
				else q.push_front({cur.f,{x,y}});
			}
		}
		
	}
	cout<<ans;
	
}

Compilation message (stderr)

tracks.cpp: In function 'void setIO(std::string)':
tracks.cpp:23:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   23 |   freopen((name + ".in").c_str(), "r", stdin);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tracks.cpp:24:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   24 |   freopen((name + ".out").c_str(), "w", stdout);
      |   ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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