Submission #259674

#	Time	Username	Problem	Language	Result	Execution time	Memory
259674		arnold518	Dangerous Skating (JOI16_skating)	C++14	100 / 100	297 ms	28268 KiB

skating

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

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 1000;
const ll INF = 1e18;

int N, M;
char S[MAXN+10][MAXN+10];
int L[MAXN+10][MAXN+10], R[MAXN+10][MAXN+10], U[MAXN+10][MAXN+10], D[MAXN+10][MAXN+10];
ll dist[MAXN+10][MAXN+10];
pii P, Q;

struct Queue
{
	int y, x; ll w;
	bool operator < (const Queue &p) const { return w>p.w; }
};
priority_queue<Queue> PQ;

void enqueue(Queue now)
{
	if(dist[now.y][now.x]<=now.w) return;
	dist[now.y][now.x]=now.w;
	PQ.push(now);
}

int main()
{
	scanf("%d%d", &N, &M);
	for(int i=1; i<=N; i++) scanf("%s", S[i]+1);
	scanf("%d%d%d%d", &P.first, &P.second, &Q.first, &Q.second);
	
	for(int i=1; i<=N; i++) for(int j=1; j<=M; j++)
	{
		if(S[i][j]=='#') U[i][j]=i;
		else U[i][j]=U[i-1][j];
		if(S[i][j]=='#') L[i][j]=j;
		else L[i][j]=L[i][j-1];
	}
	for(int i=N; i>=1; i--) for(int j=M; j>=1; j--)
	{
		if(S[i][j]=='#') D[i][j]=i;
		else D[i][j]=D[i+1][j];
		if(S[i][j]=='#') R[i][j]=j;
		else R[i][j]=R[i][j+1];
	}
	for(int i=1; i<=N; i++) for(int j=1; j<=M; j++)
	{
		L[i][j]++; R[i][j]--;
		U[i][j]++; D[i][j]--;
	}

	for(int i=1; i<=N; i++) for(int j=1; j<=M; j++) dist[i][j]=INF;

	enqueue({P.first, P.second, 0});
	enqueue({P.first, P.second, 0});

	while(!PQ.empty())
	{
		Queue now=PQ.top(); PQ.pop();
		if(dist[now.y][now.x]!=now.w) continue;

		enqueue({now.y, L[now.y][now.x], now.w+1});
		enqueue({now.y, R[now.y][now.x], now.w+1});
		if(U[now.y][now.x]<=now.y-1) enqueue({now.y-1, now.x, now.w+2});
		if(D[now.y][now.x]>=now.y+1) enqueue({now.y+1, now.x, now.w+2});
		enqueue({U[now.y][now.x], now.x, now.w+1});
		enqueue({D[now.y][now.x], now.x, now.w+1});
		if(L[now.y][now.x]<=now.x-1) enqueue({now.y, now.x-1, now.w+2});
		if(R[now.y][now.x]>=now.x+1) enqueue({now.y, now.x+1, now.w+2});
	}

	ll ans=dist[Q.first][Q.second];
	if(ans==INF) ans=-1;
	printf("%lld\n", ans);
}

Compilation message (stderr)

skating.cpp: In function 'int main()':
skating.cpp:33:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~
skating.cpp:34:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1; i<=N; i++) scanf("%s", S[i]+1);
                          ~~~~~^~~~~~~~~~~~~~
skating.cpp:35:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d", &P.first, &P.second, &Q.first, &Q.second);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 65 / 65
• Subtask 3: 22 / 22