Submission #30902

#	Time	Username	Problem	Language	Result	Execution time	Memory
30902		Navick	Portals (BOI14_portals)	C++14	70 / 100	1000 ms	93604 KiB

portals

#include <bits/stdc++.h>
#define F first
#define S second
#define pii pair<int, int>
#define pb push_back
#define end EEE

using namespace std;

typedef long long ll;
typedef long double ld;

const int N = 1010, INF = 1e9;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

//down,right,up,left.

int d[N][N], dis[N][N];
pii start, end, que[N * N], nex[4][N][N];
bool mp[N][N];
char sr[N];

set<pair<int, pii> > s;

int main(){
	int n, m; scanf("%d %d",&n ,&m);
	for(int i=1; i<=n; i++){
		scanf("%s", sr);
		for(int j=1; j<=m; j++){
			if(sr[j - 1] == '.'){
				mp[i][j] = true;
				d[i][j] = INF;
			}
			else if(sr[j - 1] == 'S'){
				mp[i][j] = true;
				d[i][j] = INF;
				start = {i, j};
			}else if(sr[j - 1] == 'C'){
				mp[i][j] = true; 
				d[i][j] = INF;
				end = {i, j};
			}
		}
	}

	int st = 0, en = 0;

	for(int i=0; i<=n+1; i++)
		for(int j=0; j<=m+1; j++)
			if(!mp[i][j])
				que[en++] = {i, j};

	while(en - st){
		pii v = que[st++];
		int x = v.F, y = v.S;
		for(int i=0; i<4; i++){
			int nx = x + dx[i], ny = y + dy[i];
			if(nx < 0 || nx > n + 1 || ny < 0 || ny > m + 1)continue;
			if(d[nx][ny] == INF){
				d[nx][ny] = d[x][y] + 1;
				que[en++] = {nx, ny};
			}
		}
	}

	for(int i=n+1; i>=0; i--)
		for(int j=m+1; j>=0; j--){
			
			if(!mp[i][j])continue;
			
			for(int c=0; c<2; c++){
				int nx = i + dx[c], ny = j + dy[c];
				if(nx < 0 || nx > n + 1 || ny < 0 || ny > m + 1)continue;
				if(mp[nx][ny])
					nex[c][i][j] = nex[c][nx][ny];
				else nex[c][i][j] = {i, j};
			}
		}

	for(int i=0; i<=n+1; i++){
		for(int j=0; j<=m+1; j++){
			
			if(!mp[i][j])continue;

			for(int c=2; c<4; c++){
				int nx = i + dx[c], ny = j + dy[c];
				if(nx < 0 || nx > n + 1 || ny < 0 || ny > m + 1)continue;
				if(mp[nx][ny])
					nex[c][i][j] = nex[c][nx][ny];
				else nex[c][i][j] = {i, j};
			}
		}
	}

	//dijkstra :)

	for(int i=0; i<=n+1; i++)
		for(int j=0; j<=m+1; j++){
			if(!mp[i][j])continue;
			dis[i][j] = INF;
			if(i != start.F || j != start.S)
				s.insert({dis[i][j], {i, j}});
		}

	dis[start.F][start.S] = 0;
	s.insert({0, start});


	while(!s.empty()){
		auto X = *(s.begin());
		s.erase(s.begin());
		int res = X.F;
		int x = X.S.F, y = X.S.S;

		for(int i=0; i<4; i++){
			int nx = x + dx[i], ny = y + dy[i];
			if(nx < 0 || nx > n + 1 || ny < 0 || ny > m + 1)continue;
			if(!mp[nx][ny])continue;
			if(dis[nx][ny] > res + 1){
				s.erase({dis[nx][ny], {nx, ny}});
				dis[nx][ny] = res + 1;
				s.insert({dis[nx][ny], {nx, ny}});
			}
		}

		for(int i=0; i<4; i++){
			int nx = nex[i][x][y].F, ny = nex[i][x][y].S;
			if(dis[nx][ny] > res + d[x][y]){
				s.erase({dis[nx][ny], {nx, ny}});
				dis[nx][ny] = res + d[x][y];
				s.insert({dis[nx][ny], {nx, ny}});
			}
		}
	}
	/*
	for(int c=0; c<4; c++){
		cout << c << endl;
		for(int i=1; i<=n; i++){
			for(int j=1; j<=m; j++)
				if(mp[i][j])cout << nex[c][i][j].F << ',' << nex[c][i][j].S << ' ';
				else cout << -1 << ',' << -1 <<  ' ';
			cout << endl;
		}
		cout << endl;
	}

	for(int i=1; i<=n; i++){
		for(int j=1; j<=m; j++)
			cout << d[i][j] << ' ';
		cout << endl;
	}
	*/
	printf("%d\n", dis[end.F][end.S]);

}

Compilation message (stderr)

portals.cpp: In function 'int main()':
portals.cpp:27:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  int n, m; scanf("%d %d",&n ,&m);
                                 ^
portals.cpp:29:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%s", sr);
                  ^

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