Submission #742956

#	Time	Username	Problem	Language	Result	Execution time	Memory
742956		Dan4Life	Portals (BOI14_portals)	C++17	0 / 100	5 ms	8412 KiB

portals

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define sz(a) (int)a.size()
const int mxN = (int)1e3+10;
int X[] = {1,-1,0,0};
int Y[] = {0,0,1,-1};
int n, m, stX, stY, enX, enY;
string a[mxN];
queue<pair<int,int>> Q;
int dis[mxN][mxN];
pair<int,int> dir[4][mxN][mxN];

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

void bfs(int i, int j){
	memset(dis,-1,sizeof(dis));
	Q.push({i,j}); dis[i][j] = 0;
	while(!Q.empty()){
		auto [i,j] = Q.front(); Q.pop();
		bool ok = 0; //cout << i << " " << j << " " << dis[i][j] << "\n";
		for(int k = 0; k < 4; k++){
			int ni = i+X[k], nj = j+Y[k];
			if(valid(ni,nj) and dis[ni][nj]==-1)
				dis[ni][nj] = dis[i][j]+1, Q.push({ni,nj});
			else if(!valid(ni,nj)) ok=1;
		}
		for(int k = 0; k < 4 and ok; k++){
			auto [ni,nj] = dir[k][i][j];
			if(valid(ni,nj) and dis[ni][nj]==-1)
				dis[ni][nj] = dis[i][j]+1, Q.push({ni,nj});
		}
	}
}

int32_t main(){
	cin >> n >> m;
	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;
		}
	}
	for(int i = 0; i < n; i++){
		int last = 0;
		for(int j = 0; j < m; j++){
			if(a[i][j]=='#') last = j+1;
			else dir[0][i][j]={i,last};
		}
		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};
		}
	}
	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]={i,last};
		}
		last = n-1;
		for(int i = n-1; i >= 0; i--){
			if(a[i][j]=='#') last = i-1;
			else dir[3][i][j]={i,last};
		}
	}
	bfs(stX,stY); cout << dis[enX][enY];
}

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