Submission #943268

#	Time	Username	Problem	Language	Result	Execution time	Memory
943268		WongYiKai	Portals (BOI14_portals)	C++14	100 / 100	540 ms	228208 KiB

portals

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

ll r,c;

ll a(ll i, ll j) {
	return (i)*(c+2)+j;
}
pair<ll,ll> ra(ll x) {
	return {(x)/(c+2),(x)%(c+2)};
}


int main(){
	ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	cin >> r >> c;
	//if (r*c>100) return 0;
	ll grid[r+5][c+5];
	ll s,e;
	memset(grid,0,sizeof(grid));
	for (int i=1;i<=r;i++){
		string temp;
		cin >> temp;
		for (int j=1;j<=c;j++){
			if (temp[j-1]=='.') grid[i][j] = 1;
			else if (temp[j-1]=='#') grid[i][j] = 0;
			else if (temp[j-1]=='C') {
				grid[i][j] = 1;
				e = a(i,j);
			}
			else{
				grid[i][j] = 1;
				s = a(i,j);
			}
		}
	}
	ll visited[r*c+r+r+c+c+10];
	queue<pair<ll,ll>> bfs;
	memset(visited,0,sizeof(visited));
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			if (grid[i][j]==0) continue;
			ll check=0;
			if (grid[i-1][j]==0) check=1;
			else if (grid[i+1][j]==0) check=1;
			else if (grid[i][j-1]==0) check=1;
			else if (grid[i][j+1]==0) check=1;
			if (check==0) continue;
			bfs.push({a(i,j),0});
			visited[a(i,j)]=1;
		}
	}
	ll dist[r*c+r+r+c+c+10];
	memset(dist,-1,sizeof(dist));
	while (!bfs.empty()){
		ll x = bfs.front().first;
		ll rnk = bfs.front().second;
		dist[x] = rnk;
		bfs.pop();
		ll item;
		pair<ll,ll> temp;
		item=x-1;
		if (visited[item]==0){
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				visited[item] = 1;
				bfs.push({item,rnk+1});
			}
		}
		item=x+1;
		if (visited[item]==0){
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				visited[item] = 1;
				bfs.push({item,rnk+1});
			}
		}
		item=x-c-2;
		if (visited[item]==0){
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				visited[item] = 1;
				bfs.push({item,rnk+1});
			}
		}
		item=x+c+2;
		if (visited[item]==0){
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				visited[item] = 1;
				bfs.push({item,rnk+1});
			}
		}
	}
	/*
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			cout << dist[a(i,j)] << " ";
		}
		cout << "\n";
	}
	*/
	ll left[r*c+r+r+c+c+10],right[r*c+r+r+c+c+10],up[r*c+r+r+c+c+10],down[r*c+r+r+c+c+10];
	for (int j=1;j<=c;j++) up[a(0,j)] = a(1,j);
	for (int i=1;i<=r;i++){
		if (grid[i][1]==0) {
			left[a(i,1)]=a(i,2);
			up[a(i,1)]=a(i+1,1);
		}
		else {
			left[a(i,1)]=a(i,1);
			up[a(i,1)] = up[a(i-1,1)];
		}
		for (int j=2;j<=c;j++){
			if (grid[i][j]==0) {
				left[a(i,j)] = a(i,j+1);
				up[a(i,j)] = a(i+1,j);
			}
			else {
				left[a(i,j)] = left[a(i,j-1)];
				up[a(i,j)] = up[a(i-1,j)];
			}
		}
	}
	//right down
	for (int j=1;j<=c;j++) down[a(r+1,j)] = a(r,j);
	for (int i=r;i>=1;i--){
		if (grid[i][c]==0) {
			right[a(i,c)]=a(i,c-1);
			down[a(i,c)]=a(i-1,c);
		}
		else {
			right[a(i,c)]=a(i,c);
			down[a(i,c)] = down[a(i+1,c)];
		}
		for (int j=c-1;j>=1;j--){
			if (grid[i][j]==0) {
				right[a(i,j)] = a(i,j-1);
				down[a(i,j)] = a(i-1,j);
			}
			else {
				right[a(i,j)] = right[a(i,j+1)];
				down[a(i,j)] = down[a(i+1,j)];
			}
		}
	}
	/*
	cout << "left\n";
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			cout << ra(left[a(i,j)]).first << "," << ra(left[a(i,j)]).second << " ";
		}
		cout << "\n";
	}
	cout << "right\n";
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			cout << ra(right[a(i,j)]).first << "," << ra(right[a(i,j)]).second << " ";
		}
		cout << "\n";
	}
	cout << "down\n";
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			cout << ra(down[a(i,j)]).first << "," << ra(down[a(i,j)]).second << " ";
		}
		cout << "\n";
	}
	cout << "up\n";
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			cout << ra(up[a(i,j)]).first << "," << ra(up[a(i,j)]).second << " ";
		}
		cout << "\n";
	}
	*/
	
	vector<pair<ll,ll>> adj[r*c+r+r+c+c+10];
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			if (grid[i][j]==0) continue;
			ll x = a(i,j);
			ll item;
			pair<ll,ll> temp;
			item=x-1;
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				adj[x].push_back({item,1});
			}
			item=x+1;
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				adj[x].push_back({item,1});
			}
			item=x-c-2;
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				adj[x].push_back({item,1});
			}
			item=x+c+2;
			temp = ra(item);
			if (grid[temp.first][temp.second]==1){
				adj[x].push_back({item,1});
			}
			adj[x].push_back({left[x],max(0LL,dist[x])+1});
			adj[x].push_back({down[x],max(0LL,dist[x])+1});
			adj[x].push_back({up[x],max(0LL,dist[x])+1});
			adj[x].push_back({right[x],max(0LL,dist[x])+1});
		}
	}
	
	/*
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			cout << i << "," << j << ": ";
			for (auto item:adj[a(i,j)]){
				cout << ra(item.first).first << "," << ra(item.first).second << "," << item.second << " ";
			}
			cout << "\n";
		}
	}
	*/
	
	ll dis[r*c+r+r+c+c+10];
	priority_queue<pair<ll,ll>,vector<pair<ll,ll>>,greater<pair<ll,ll>>> pq;
	memset(dis,-1,sizeof(dis));
	dis[s]=0;
	pq.push({0,s});
	while (!pq.empty())	{
		pair<ll,ll> cur = pq.top();
		pq.pop();
		ll x = cur.second, d = cur.first;
		if (d>dis[x]) continue;
		for (vector<pair<ll,ll>>::iterator it=adj[x].begin();it!=adj[x].end();++it){
			ll nx = it->first, nd = d+it->second;
			if (nx>a(r,c) || nx<a(1,1)) continue;
			if (dis[nx]!=-1 && dis[nx]<=nd) continue;
			dis[nx] = nd;
			pq.push({nd,nx});
		}
	}
	
	/*
	for (int i=1;i<=r;i++){
		for (int j=1;j<=c;j++){
			cout << dis[a(i,j)] << " ";
		}
		cout << "\n";
	}
	*/
	cout << dis[e];	
	//cout << "a";
	
}

Compilation message (stderr)

portals.cpp: In function 'int main()':
portals.cpp:252:15: warning: 'e' may be used uninitialized in this function [-Wmaybe-uninitialized]
  252 |  cout << dis[e];
      |               ^

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