Submission #1120885

#	Time	Username	Problem	Language	Result	Execution time	Memory
1120885		vjudge1	Tracks in the Snow (BOI13_tracks)	C++17	43.13 / 100	2142 ms	953624 KiB

tracks

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define run  ios_base::sync_with_stdio(false);cin.tie(0);
 
#define ll int
#define pll pair<ll, ll>
#define ull unsigned ll
#define ld double
#define endl "\n"
#define pb push_back
#define fi first
#define se second
 
#define pi acos(-1)
#define N 4007
#define minimum -9223372036854775807
#define maximum -minimum
#define mod 1000000007
 
using namespace std;
using namespace __gnu_pbds;
template <class t>
using ordered_set=tree<t, null_type,less_equal<t>, rb_tree_tag,tree_order_statistics_node_update>;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

ll gcd(ll a, ll b)
{
	if(b==0)
		return a;
	return gcd(b, a%b);
}

ll lcm(ll a, ll b)
{
	return a/gcd(a, b)*b;
}

bool isprime(ll n)
{
	if(n==1)
		return 0;
	for(ll i=2; i*i<=n; i++)
	{
		if(n%i==0)
			return 0;
	}
	return 1;
}

ll binpow(ll a, ll b)
{
    a%=mod;
    ll res=1;
    while(b>0)
	{
        if(b%2==1)
            res=(res*a)%mod;
        a=(a*a)%mod;
        b/=2;
    }
    return res;
}

ll dx[]={0, 0, 1, -1};
ll dy[]={1, -1, 0, 0};
ll h, w, cvb;
char a[N][N];
bool used[N][N];

bool inbound(ll x, ll y)
{
	return 1<=x && x<=h && 1<=y && y<=w;
}

void dfs(ll x, ll y, char z)
{
	used[x][y]=1;
	for(ll i=0; i<4; i++)
	{
		ll nx=x+dx[i];
		ll ny=y+dy[i];
		if(inbound(nx, ny) && (a[nx][ny]!=z && a[nx][ny]!='.') && !used[nx][ny])
		{
			dfs(nx, ny, z);
		}
	}
}

int main()
{
//	run;
	cin>>h>>w;
	for(ll i=1; i<=h; i++)
	{
		for(ll j=1; j<=w; j++)
		{
			cin>>a[i][j];
		}
	}
	ll cvb=1;
	while(true)
	{
		set<char>st;
		st.clear();
		for(ll i=1; i<=h; i++)
		{
			for(ll j=1; j<=w; j++)
			{
				if(a[i][j]!='.')
					st.insert(a[i][j]);
			}
		}
		if(st.size()==1)
			break;
		for(ll i=1; i<=h; i++)
		{
			for(ll j=1; j<=w; j++)
			{
				used[i][j]=0;
			}
		}
		if(a[h][w]=='F')
			dfs(h, w, 'R');
		else
			dfs(h, w, 'F');
		for(ll i=1; i<=h; i++)
		{
			for(ll j=1; j<=w; j++)
			{
				if(used[i][j])
				{
					if(a[h][w]=='F')
						a[i][j]='R';
					else
						a[i][j]='F';
				}
//				cout<<a[i][j];
			}
//			cout<<endl;
		}
		cvb++;
	}
	cout<<cvb<<endl;
}
/*
RRRR
R..R
R..R
RRRR
*/
// By Xanlar

• Subtask 1: 30 / 30
• Subtask 2: 13.125 / 70