제출 #890537

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
890537		thunopro	Tracks in the Snow (BOI13_tracks)	C++14	100 / 100	644 ms	128612 KiB

tracks

#include<bits/stdc++.h>
using namespace std ; 
#define maxn 4009 
#define ll long long 
#define fi first 
#define se second 
#define pb push_back 
#define left id<<1 
#define right id<<1|1
#define re exit(0);
#define _lower(v,x) lower_bound(v.begin(),v.end(),x)-v.begin()+1

const int mod = 1e9+7 ; 
const int INF = 1e9 ;
const int LOG = 18 ; 

typedef vector<int> vi ; 
typedef pair<int,int> pii ; 
typedef vector<pii> vii ;
typedef vector<ll> vl ;  
typedef pair<ll,ll> pll ; 
typedef vector<pll> vll ; 

void add ( int&a , int b ) { if ((a+=b) > mod ) a -= mod ; } 
void sub ( int&a , int b ) { if ((a-=b) < 0 ) a += mod ; } 
template<typename T> void chkmin(T& x, T y) {if(x > y) x = y;}
template<typename T> void chkmax(T& x, T y) {if(x < y) x = y;}

void rf ( ) 
{
	freopen ("bai1.inp","r",stdin) ; 
//	freopen ("bai1.out","w",stdout) ;
}

int _pow ( int a , int n ) 
{
	if ( n == 0 ) return 1 ; 
	int res = _pow ( a , n / 2 ) ; 
	if ( n % 2 ) return ( 1ll * res * res % mod * a % mod ) ; 
	else return ( 1ll * res * res % mod ) ; 
}

int n , m ; 
char a [maxn][maxn] ; 

int dx [] = {0,0,-1,1} ; 
int dy [] = {1,-1,0,0} ;
bool inside ( int x , int y ) 
{
	return (x>=1&&x<=n&&y>=1&&y<=m&&a[x][y]!='.') ; 
}

int d [maxn][maxn] ; 
int main ( ) 
{
	ios_base :: sync_with_stdio (0) ; 
	cin.tie(0) ; cout.tie(0) ;
//	rf () ; 
	cin >> n >> m ; 
	for ( int i = 1 ; i <= n ; i ++ ) for ( int j = 1 ; j <= m ; j ++ ) cin >> a [i][j] ; 
	
	deque <pii> q ; 
	memset ( d , 0x3f , sizeof d ) ; 
	d [1][1] = 1 ; 
	q . pb ({1,1}) ; 
	while (!q.empty()) 
	{
		int u = q.front().fi , v = q.front().se ; 
		q.pop_front() ; 
		for ( int i = 0 ; i < 4 ; i ++ ) 
		{
			int x = u + dx [i] , y = v + dy [i] ; 
			if ( inside (x,y) ) 
			{
				if ( a [x][y] == a [u][v] && d[x][y]>d[u][v] ) q.push_front({x,y}) , d [x][y] = d [u][v] ; 
				else if ( d [x][y] > d [u][v] + 1 ) 
				{
					q . pb ({x,y}) ; 
					d [x][y] = d [u][v] + 1 ; 
				}
			}
		}
	}
	int res = 0 ; 
	for ( int i = 1 ; i <= n ; i ++ ) for ( int j = 1 ; j <= m ; j ++ ) 
	{
		if ( a[i][j] == '.' ) continue ; 
		chkmax (res,d[i][j]) ; 
	}
	cout << res ; 
}




//-std=c++11

컴파일 시 표준 에러 (stderr) 메시지

tracks.cpp: In function 'void rf()':
tracks.cpp:31:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |  freopen ("bai1.inp","r",stdin) ;
      |  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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