Submission #259668

#	Time	Username	Problem	Language	Result	Execution time	Memory
259668		arnold518	Dangerous Skating (JOI16_skating)	C++14	78 / 100	3059 ms	132816 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];
pii P, Q;

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

ll dist[MAXN+10][MAXN+10][2];

void enqueue(Queue now)
{
	if(dist[now.y][now.x][now.d]<=now.w) return;
	dist[now.y][now.x][now.d]=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++) for(int k=0; k<2; k++) dist[i][j][k]=INF;

	enqueue({P.first, P.second, 0, 0});
	enqueue({P.first, P.second, 1, 0});

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

		if(now.d==0)
		{
			for(int i=L[now.y][now.x]; i<now.x; i++) enqueue({now.y, i, 1, now.w+min(1+(i-L[now.y][now.x])*2, (now.x-i)*2)});
			for(int i=now.x+1; i<=R[now.y][now.x]; i++) enqueue({now.y, i, 1, now.w+min(1+(R[now.y][now.x]-i)*2, (i-now.x)*2)});
		}
		else
		{
			for(int i=U[now.y][now.x]; i<now.y; i++) enqueue({i, now.x, 0, now.w+min(1+(i-U[now.y][now.x])*2, (now.y-i)*2)});
			for(int i=now.y+1; i<=D[now.y][now.x]; i++) enqueue({i, now.x, 0, now.w+min(1+(D[now.y][now.x]-i)*2, (i-now.y)*2)});
		}
	}
	ll ans=min(dist[Q.first][Q.second][0], dist[Q.first][Q.second][1]);
	if(ans==INF) ans=-1;
	printf("%lld\n", ans);
}

Compilation message (stderr)

skating.cpp: In function 'int main()':
skating.cpp:34:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~
skating.cpp:35:31: 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:36:7: 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: 0 / 22