【CodeVS 3290】【NOIP 2013】华容道

#include<queue>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int N = 33;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, 1, 0, -1};
int in() {
	int k = 0, fh = 1; char c = getchar();
	for(; c < ‘0‘ || c > ‘9‘; c = getchar())
		if (c == ‘-‘) fh = -1;
	for(; c >= ‘0‘ && c <= ‘9‘; c = getchar())
		k = (k << 3) + (k << 1) + c - ‘0‘;
	return k * fh;
}

struct node {int nxt, to, w;} E[20003];
int Move[33][33][4][4], point[4003], cnt = 0, a[33][33], n, m, qq;
int number[33][33][4], tot = 0;

void ins(int u, int v, int w) {E[++cnt] = (node) {point[u], v, w}; point[u] = cnt;}

bool can(int x, int y) {
	return ((x >= 1) && (x <= n) && (y >= 1) && (y <= m) && (a[x][y] == 1));
}

struct Point {
	int x, y, d;
	Point(int _x = 0, int _y = 0, int _d = 0) : x(_x), y(_y), d(_d) {}
	bool operator == (const Point &A) const {
		return x == A.x && y == A.y;
	}
} q[1003];

int cross(int x, int y, int h, int hh) {
	Point s, t;
	s = Point(x + dx[h], y + dy[h], 0);
	t = Point(x + dx[hh], y + dy[hh], 0);
	a[x][y] = 0;
	int head = 0, tail = 1;
	q[1] = s; a[s.x][s.y] = 1;
	
	Point u, v;
	while (head != tail) {
		u = q[++head];
		if (u == t) break;
		for(int d = 0; d < 4; ++d)
			if (can(u.x + dx[d], u.y + dy[d])) {
				v = Point(u.x + dx[d], u.y + dy[d], u.d + 1);
				q[++tail] = v;
				a[v.x][v.y] = 0;
			}
	}
	
	for(int i = 1; i <= tail; ++i)
		a[q[i].x][q[i].y] = 1;
	
	a[x][y] = 1;
	if (u == t)	return u.d;
	else return 0x7fffffff;
}

void dealwith(int x, int y) {
	int ed;
	for(int d = 0; d < 4; ++d)
		if (can(x + dx[d], y + dy[d]))
			for(int dd = d + 1; dd < 4; ++dd)
				if (can(x + dx[dd], y + dy[dd])) {
					ed = Move[x][y][d][dd] = Move[x][y][dd][d] = cross(x, y, d, dd);
					if (ed != 0x7fffffff) {
						ins(number[x][y][d], number[x][y][dd], ed);
						ins(number[x][y][dd], number[x][y][d], ed);
					}
				}
}

int dis(Point g, Point s, Point t) {
	int head = 0, tail = 1;
	s.d = 0; q[1] = s; a[s.x][s.y] = 0; a[g.x][g.y] = 0;
	Point u, v;
	while (head != tail) {
		u = q[++head];
		if (u == t) break;
		for(int d = 0; d < 4; ++d)
			if (can(u.x + dx[d], u.y + dy[d])) {
				v = Point(u.x + dx[d], u.y + dy[d], u.d + 1);
				q[++tail] = v;
				a[v.x][v.y] = 0;
			}
	}
	
	a[g.x][g.y] = 1;
	for(int i = 1; i <= tail; ++i)
		a[q[i].x][q[i].y] = 1;
	if (u == t) return u.d;
	else return 0x7fffffff;
}

queue <int> Q;
int dist[4003], inq[4003];

void spfa(int s) {
	memset(dist, 127, sizeof(int) * (tot + 1));
	Q.push(s); dist[s] = 0; inq[s] = true;
	int u;
	while (!Q.empty()) {
		u = Q.front(); Q.pop(); inq[u] = false;
		for(int i = point[u]; i; i = E[i].nxt)
			if (dist[u] + E[i].w < dist[E[i].to]) {
				dist[E[i].to] = dist[u] + E[i].w;
				if (!inq[E[i].to]) {
					Q.push(E[i].to);
					inq[E[i].to] = true;
				}
			}
	}
}

int main() {
	n = in(); m = in(); qq = in();
	for(int i = 1; i <= n; ++i)
		for(int j = 1; j <= m; ++j)
			a[i][j] = in();
	
	for(int i = 1; i <= n; ++i)
		for(int j = 1; j <= m; ++j)
			if (a[i][j] == 1)
				for(int d = 0; d < 4; ++d)
					if (can(i + dx[d], j + dy[d]))
						number[i][j][d] = ++tot;
	
	for(int i = 1; i <= n; ++i)
		for(int j = 1; j <= m; ++j)
			if (a[i][j] == 1) dealwith(i, j);
	
	for(int i = 1; i <= n; ++i)
		for(int j = 1; j <= m; ++j)
			if (a[i][j] == 1)
				for(int d = 0; d < 4; ++d)
					if (can(i + dx[d], j + dy[d]))
						ins(number[i][j][d], number[i + dx[d]][j + dy[d]][(d + 2) % 4], 1);
	
	++tot;
	Point e, s, t;
	int now = cnt, ans;
	while (qq--) {
		e.x = in(); e.y = in(); s.x = in(); s.y = in(); t.x = in(); t.y = in();
		if (s == t) {puts("0"); continue;}
		cnt = now; point[tot] = 0;
		for(int d = 0; d < 4; ++d)
			if (can(s.x + dx[d], s.y + dy[d]))
				ins(tot, number[s.x][s.y][d], dis(s, e, Point(s.x + dx[d], s.y + dy[d], 0)));
		spfa(tot);
		ans = 0x7fffffff;
		for(int d = 0; d < 4; ++d)
			ans = min(ans, dist[number[t.x][t.y][d]]);
		printf("%d\n", ans == 2139062143 ? -1 : ans);
	}
	
	return 0;
}