Submission #287390

#	Time	Username	Problem	Language	Result	Execution time	Memory
287390		Namnamseo	Portals (BOI14_portals)	C++17	100 / 100	641 ms	92792 KiB

portals

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pp;
typedef pair<ll,ll> pll;
void read(int& x){ scanf("%d",&x); }
void read(ll& x){ scanf("%lld",&x); }
template<typename T,typename... Args>
void read(T& a,Args&... b){ read(a); read(b...); }
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define eb emplace_back
#define x first
#define y second

int n, m;

inline int enc(int r, int c){ return (r-1)*m + c; }

char z[1010][1010];
int aL[1010][1010], aR[1010][1010], aD[1010][1010], aU[1010][1010];

void bm(){
	for(int i=1; i<=n; ++i){
		aL[i][0] = 1;
		for(int j=1; j<=m; ++j){
			aL[i][j] = aL[i][j-1];
			if(z[i][j] == '#') aL[i][j]=j+1;
		}
		aR[i][m+1] = m;
		for(int j=m; 1<=j; --j){
			aR[i][j] = aR[i][j+1];
			if(z[i][j] == '#') aR[i][j]=j-1;
		}
	}
	for(int j=1; j<=m; ++j){
		aU[0][j] = 1;
		for(int i=1; i<=n; ++i){
			aU[i][j] = aU[i-1][j];
			if(z[i][j] == '#') aU[i][j]=i+1;
		}
		aD[n+1][j] = n;
		for(int i=n; 1<=i; --i){
			aD[i][j] = aD[i+1][j];
			if(z[i][j] == '#') aD[i][j]=i-1;
		}
	}
}

vector<pp> e[1001*1001];
void be(){
	for(int i=1; i<=n; ++i){
		for(int j=1; j<=m; ++j){
			if(z[i][j]=='#') continue;
			int nd = 1e9;
			nd = min(nd, j - aL[i][j]);
			nd = min(nd, i - aU[i][j]);
			nd = min(nd, aR[i][j] - j);
			nd = min(nd, aD[i][j] - i);
			nd += 1;
			int me = enc(i, j);
			auto f = [&](int a, int b){
				//printf("%d,%d -> %d,%d\n", i, j, a, b);
				e[me].eb(enc(a, b), nd);
			};
			f(i, aL[i][j]);
			f(i, aR[i][j]);
			f(aU[i][j], j);
			f(aD[i][j], j);
			//putchar(10);
		}
	}
}

int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};

pp sp, ep;

priority_queue<pp> pq;
int dist[1001*1001];

int main()
{
	read(n, m);
	for(int i=1; i<=n; ++i){
		scanf("%s", z[i]+1);
		for(int j=1; j<=m; ++j){
			if(z[i][j] == 'S') sp={i, j};
			if(z[i][j] == 'C') ep={i, j};
		}
	}
	bm();
	be();
	int V = n*m;
	for(int i=1; i<=V; ++i) dist[i] = 1e9;
	int s = enc(sp.x, sp.y);
	dist[s]=0; pq.emplace(0, s);
	while(pq.size()){
		int d, p; tie(d, p)=pq.top(); pq.pop();
		if(-d != dist[p]) continue;
		int x=1+(p-1)/m, y=p-(x-1)*m;
		for(int d=0; d<4; ++d){
			int nx=x+dx[d], ny=y+dy[d];
			if(1<=nx && 1<=ny && nx<=n && ny<=m && z[nx][ny] != '#'){
				int np=enc(nx, ny);
				if(dist[np] > dist[p]+1){
					dist[np] = dist[p] + 1;
					pq.emplace(-dist[np], np);
				}
			}
		}
		for(auto t:e[p]){
			int q, d; tie(q, d)=t;
			if(dist[q] > dist[p]+d){
				dist[q] = dist[p]+d;
				pq.emplace(-dist[q], q);
			}
		}
	}
	printf("%d\n", dist[enc(ep.x, ep.y)]);
	return 0;
}

Compilation message (stderr)

portals.cpp: In function 'void read(int&)':
portals.cpp:6:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    6 | void read(int& x){ scanf("%d",&x); }
      |                    ~~~~~^~~~~~~~~
portals.cpp: In function 'void read(ll&)':
portals.cpp:7:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    7 | void read(ll& x){ scanf("%lld",&x); }
      |                   ~~~~~^~~~~~~~~~~
portals.cpp: In function 'int main()':
portals.cpp:87:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   87 |   scanf("%s", z[i]+1);
      |   ~~~~~^~~~~~~~~~~~~~

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