Submission #742988

#	Time	Username	Problem	Language	Result	Execution time	Memory
742988		Dan4Life	Portals (BOI14_portals)	C++17	100 / 100	410 ms	44140 KiB

portals

#include <bits/stdc++.h>
using namespace std;
#define sz(a) (int)a.size()
const int mxN = (int)1e3+10;
using ar = array<int,3>;
int X[] = {1,-1,0,0};
int Y[] = {0,0,1,-1};

string a[mxN];
bool vis[mxN][mxN];
int n, m, stX, stY, enX, enY;
pair<int,int> dir[4][mxN][mxN];
int dis[mxN][mxN], sh[mxN][mxN];
priority_queue<ar,vector<ar>,greater<ar>> pq;

bool valid(int i, int j){
	return i>=0 and j>=0 and i<n and j<m and a[i][j]!='#';
}

void dijkstra(int sti, int stj){
	memset(dis,63,sizeof(dis));
	pq.push({0,sti,stj}); dis[sti][stj] = 0;
	while(!pq.empty()){
		auto [w,i,j] = pq.top();  pq.pop();
		if(vis[i][j]) continue; vis[i][j]=1;
		for(int k = 0; k < 4; k++){
			int ni = i+X[k], nj = j+Y[k];
			if(valid(ni,nj) and dis[ni][nj]>dis[i][j]+1)
				dis[ni][nj] = dis[i][j]+1, pq.push({dis[ni][nj],ni,nj});
		}
		for(int k = 0; k < 4; k++){
			auto [ni,nj] = dir[k][i][j];
			if(valid(ni,nj) and dis[ni][nj]>dis[i][j]+sh[i][j])
				dis[ni][nj] = dis[i][j]+sh[i][j], pq.push({dis[ni][nj],ni,nj});
		}
	}
}

int32_t main(){
	cin >> n >> m; memset(sh,63,sizeof(sh));
	for(int i = 0; i < n; i++){
		cin >> a[i];
		for(int j = 0; j < m; j++){
			if(a[i][j]=='C') enX=i,enY=j;
			else if(a[i][j]=='S') stX=i,stY=j;
		}
		int last = 0;
		for(int j = 0; j < m; j++){
			if(a[i][j]=='#') last = j+1;
			else{
				dir[0][i][j]={i,last};
				sh[i][j]=min(sh[i][j],abs(last-j)+1);
			}
		}
		last = m-1;
		for(int j = m-1; j >= 0; j--){
			if(a[i][j]=='#') last = j-1;
			else{
				dir[1][i][j]={i,last};
				sh[i][j]=min(sh[i][j],abs(last-j)+1);
			}
		}
	}
	for(int j = 0; j < m; j++){
		int last = 0;
		for(int i = 0; i < n; i++){
			if(a[i][j]=='#') last = i+1;
			else{
				dir[2][i][j]={last,j};
				sh[i][j]=min(sh[i][j],abs(last-i)+1);
			}
		}
		last = n-1;
		for(int i = n-1; i >= 0; i--){
			if(a[i][j]=='#') last = i-1;
			else{
				dir[3][i][j]={last,j};
				sh[i][j]=min(sh[i][j],abs(last-i)+1);
			}
		}
	}
	dijkstra(stX,stY); cout << dis[enX][enY];
}

Compilation message (stderr)

portals.cpp: In function 'void dijkstra(int, int)':
portals.cpp:25:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   25 |   if(vis[i][j]) continue; vis[i][j]=1;
      |   ^~
portals.cpp:25:27: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   25 |   if(vis[i][j]) continue; vis[i][j]=1;
      |                           ^~~

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