Submission #235275

#	Time	Username	Problem	Language	Result	Execution time	Memory
235275		Goolakh	Portals (BOI14_portals)	C++17	100 / 100	321 ms	28224 KiB

portals

/// Be Kind :)
#include <bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O2")
#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("Os")

/*				Bitch, where you when I was walkin'?
				Now I run the game, got the whole world talkin'				*/

/*				You never likes us anyway, fuck your friendship, I meant it */

/*				The Chanel or Balenciaga, Louis and Vuitton
				She know I got Fendi, Prada when I hit Milan				*/

/*				Niggas been counting me out
				I'm counting my bullets, I'm loading my clips
				I'm writing down names, I'm making a list					*/

/*				I ran away, I don't think I'm coming back home				*/

#define F first
#define S second
#define pb push_back
#define SZ(x) (ll)(x.size())
#define all(x) x.begin(),x.end()

typedef int ll;
typedef pair<ll,ll> pll;

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

const ll maxn=1e3+10, maxm=51, lg=23, mod=1e9+7, inf=1e18;

ll dx[]={1,0,-1,0};
ll dy[]={0,1,0,-1};

char bb[maxn][maxn];
ll ww[maxn][maxn],dis[maxn][maxn];
bool mk[maxn][maxn];
ll U[maxn][maxn],D[maxn][maxn],L[maxn][maxn],R[maxn][maxn];

priority_queue<pll,vector<pll>,greater<pll>> pq;
void midi(ll x,ll y,ll d){
	if(dis[x][y]>d) dis[x][y]=d, pq.push({dis[x][y],x*maxn+y});
}

int main(){
	ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	
	ll n,m;
	cin>>n>>m;
	for(int i=1;i<=n;i++)for(int j=1;j<=m;j++) ww[i][j]=min({i,j,n-i+1,m-j+1});
	deque<ll> q;
	ll sx,sy,ex,ey;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			cin>>bb[i][j];
			if(bb[i][j]=='S')      sx=i,sy=j, bb[i][j]='.';
			else if(bb[i][j]=='C') ex=i,ey=j, bb[i][j]='.';
			else if(bb[i][j]=='#'){
				ww[i][j]=0;
				q.pb(i*maxn+j);
			}
		}
	}
	while(!q.empty()){
		ll x=q.front()/maxn, y=q.front()%maxn; q.pop_front();
		for(int k:{0,1,2,3}){
			ll i=x+dx[k], j=y+dy[k];
			if(bb[i][j]=='.'){
				if(ww[i][j]>ww[x][y]+1) ww[i][j]=ww[x][y]+1, q.pb(i*maxn+j);
			}
		}
	}
	for(int i=1;i<=n;i++)for(int j=1;j<=m;j++){
		U[i][j]=(bb[i-1][j]=='.' ? U[i-1][j]:i*maxn+j);
		L[i][j]=(bb[i][j-1]=='.' ? L[i][j-1]:i*maxn+j);
	}
	for(int i=n;i>=1;i--)for(int j=m;j>=1;j--){
		D[i][j]=(bb[i+1][j]=='.' ? D[i+1][j]:i*maxn+j);
		R[i][j]=(bb[i][j+1]=='.' ? R[i][j+1]:i*maxn+j);
	}
	memset(dis,69,sizeof(dis));
	dis[sx][sy]=0;
	pq.push({dis[sx][sy],sx*maxn+sy});
	while(!pq.empty()){
		ll x=pq.top().S/maxn, y=pq.top().S%maxn; pq.pop();
		if(mk[x][y]) continue;
		for(int k:{0,1,2,3}){
			int i=x+dx[k], j=y+dy[k];
			if(bb[i][j]=='.') midi(i,j,dis[x][y]+1);
		}
		midi(R[x][y]/maxn,R[x][y]%maxn,dis[x][y]+ww[x][y]);
		midi(U[x][y]/maxn,U[x][y]%maxn,dis[x][y]+ww[x][y]);
		midi(L[x][y]/maxn,L[x][y]%maxn,dis[x][y]+ww[x][y]);
		midi(D[x][y]/maxn,D[x][y]%maxn,dis[x][y]+ww[x][y]);
	}
	cout<<dis[ex][ey];
	
	return 0;
}

Compilation message (stderr)

portals.cpp:34:54: warning: overflow in implicit constant conversion [-Woverflow]
 const ll maxn=1e3+10, maxm=51, lg=23, mod=1e9+7, inf=1e18;
                                                      ^~~~
portals.cpp: In function 'int main()':
portals.cpp:100:18: warning: 'ey' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<dis[ex][ey];
                  ^
portals.cpp:100:18: warning: 'ex' may be used uninitialized in this function [-Wmaybe-uninitialized]
portals.cpp:87:30: warning: 'sy' may be used uninitialized in this function [-Wmaybe-uninitialized]
  pq.push({dis[sx][sy],sx*maxn+sy});
                       ~~~~~~~^~~
portals.cpp:87:25: warning: 'sx' may be used uninitialized in this function [-Wmaybe-uninitialized]
  pq.push({dis[sx][sy],sx*maxn+sy});
                       ~~^~~~~

• Subtask 1: 11 / 11
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 19 / 19
• Subtask 5: 30 / 30