Submission #206801

#	Time	Username	Problem	Language	Result	Execution time	Memory
206801		MvC	Tracks in the Snow (BOI13_tracks)	C++11	100 / 100	1383 ms	115440 KiB

tracks

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define mkp make_pair
#define in insert
#define er erase
#define fd find
#define fr first
#define sc second
typedef long long ll;
typedef long double ld;
const ll INF=0x3f3f3f3f3f3f3f3f;
const ll llinf=(1LL<<62);
const int inf=(1<<30);
const int nmax=4e3+50;
const int mod=1e9+7;
using namespace std;
int n,m,i,j,rs,ix,jx,viz[nmax][nmax],t,di[5],dj[5];
char c[nmax][nmax],cur;
queue<pair<int,int> >q,q1;
bool ok(int x,int y)
{
	if(x<1 || x>n || y<1 || y>m || viz[x][y] || c[x][y]=='.')return 0;
	return 1;
}
int main()
{
	//freopen("sol.in","r",stdin);
	//freopen("sol.out","w",stdout);
	//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
	ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
	di[0]=-1,di[1]=1,dj[2]=-1,dj[3]=1;
	cin>>n>>m;
	for(i=1;i<=n;i++)for(j=1;j<=m;j++)cin>>c[i][j];
	cur=c[1][1];
	viz[1][1]=1;
	q.push(mkp(1,1));
	for(rs=1;;rs++)
	{
		while(!q.empty())
		{
			i=q.front().fr,j=q.front().sc;
			q.pop();
			for(t=0;t<4;t++)
			{
				ix=i+di[t],jx=j+dj[t];
				if(!ok(ix,jx))continue;
				viz[ix][jx]=1;
				if(c[ix][jx]==cur)q.push(mkp(ix,jx));
				else q1.push(mkp(ix,jx));
			}
		}
		if(q1.empty())break;
		q=q1;
		while(!q1.empty())q1.pop();
		if(cur=='F')cur='R';
		else cur='F';
	}
	cout<<rs<<endl;
	return 0;
}

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