Submission #1097646

#	Time	Username	Problem	Language	Result	Execution time	Memory
1097646		vako_p	Portals (BOI14_portals)	C++14	70 / 100	261 ms	262144 KiB

portals

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back

const int mxN = 2e6 + 5, mxN1 = 2005;
ll n,m,dis[mxN],dis1[mxN],st,fi,idx[mxN1][mxN1];
pair<ll,ll> wall[mxN][5];
char a[mxN1][mxN1];
bool vis[mxN];
vector<pair<ll,ll>> v[mxN];
queue<ll> qq;
priority_queue<pair<ll,ll>, vector<pair<ll,ll>>, greater<pair<ll,ll>>> q;

void bfs(){
	while(!qq.empty()){
		ll at = qq.front(); qq.pop();
		for(auto it1 : v[at]){
			ll it = it1.first;
			if(vis[it]) continue;
			dis1[it] = dis1[at] + 1;
			vis[it] = true;
			qq.push(it);
		}
	}
}

void f(){
	for(int i = 0; i <= n + 1; i++){
		for(int j = 0; j <= m + 1; j++){
			if(a[i][j] == '#'){
				wall[idx[i][j]][0] = make_pair(i, j + 1);
				wall[idx[i][j]][1] = make_pair(i + 1, j);
			}	
			else{
				wall[idx[i][j]][0] = wall[idx[i][j - 1]][0];
				wall[idx[i][j]][1] = wall[idx[i - 1][j]][1];
			} 
		}	
	}
	for(int i = n + 1; i >= 0; i--){
		for(int j = m + 1; j >= 0; j--){
			if(a[i][j] == '#'){
				wall[idx[i][j]][2] = make_pair(i, j - 1);
				wall[idx[i][j]][3] = make_pair(i - 1, j);
			}
			else{
				wall[idx[i][j]][2] = wall[idx[i][j + 1]][2];
				wall[idx[i][j]][3] = wall[idx[i + 1][j]][3];
			}
			if(a[i][j] == '#') continue;
			for(int k = 0; k < 4; k++){
				pair<ll,ll> x = wall[idx[i][j]][k];
				if(abs(x.first - i) + abs(x.second - j) > dis1[idx[i][j]]){
					v[idx[i][j]].pb({x.first * (m + 2) + x.second, dis1[idx[i][j]]});
				}
			}
		}
	}
}

void dijkstra(){
	for(int i = 1; i < mxN; i++){
		dis[i] = 1e9;
		vis[i] = false;
	}
	q.push({0, st});
	dis[st] = 0;
	while(!q.empty()){
		ll at = q.top().second; q.pop();
		if(vis[at]) continue;
		vis[at] = true;
//		cout << at / (m + 2) << ' ' << at % (m + 2) << ' ' << dis[at] << ' ' << '\n';
		for(auto it : v[at]){
			if(vis[it.first]) continue;
			if(dis[it.first] > dis[at] + it.second){
				dis[it.first] = dis[at] + it.second;
				q.push({dis[it.first], it.first});
			}
		}
	}
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> m;
	for(int i = 0; i <= n + 1; i++){
		for(int j = 0; j <= m + 1; j++){
			if(i == 0 or i == n + 1 or j == 0 or j == m + 1) a[i][j] = '#';
			else cin >> a[i][j];
			idx[i][j] = i * (m + 2) + j;
			if(a[i][j] == '#') qq.push(idx[i][j]);
			if(a[i][j] == 'S'){
				st = idx[i][j];
				a[i][j] = '.';
			}
			if(a[i][j] == 'C'){
				fi = idx[i][j];
				a[i][j] = '.';
			}
		}
	}
	for(int i = 0; i <= n + 1; i++){
		for(int j = 0; j <= m + 1; j++){
			if(i > 0 and a[i - 1][j] != '#') v[idx[i][j]].pb({idx[i - 1][j], 1});
			if(i < n + 1 and a[i + 1][j] != '#') v[idx[i][j]].pb({idx[i + 1][j], 1});
			if(j > 0 and a[i][j - 1] != '#') v[idx[i][j]].pb({idx[i][j - 1], 1});
			if(j < m + 1 and a[i][j + 1] != '#') v[idx[i][j]].pb({idx[i][j + 1], 1});  
		}
	}
 	bfs();
 	f();
 	dijkstra(); 
 	cout << dis[fi]; 
}

• Subtask 1: 11 / 11
• Subtask 2: 20 / 20
• Subtask 3: 20 / 20
• Subtask 4: 19 / 19
• Subtask 5: 0 / 30