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HauntedGraveyard.java
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HauntedGraveyard.java
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// Using Reader class
import java.io.*;
import java.util.*;
public class HauntedGraveyard {
static class Reader {
final private int BUFFER_SIZE = 1 << 16;
private DataInputStream din;
private byte[] buffer;
private int bufferPointer, bytesRead;
public Reader() {
din = new DataInputStream(System.in);
buffer = new byte[BUFFER_SIZE];
bufferPointer = bytesRead = 0;
}
public int nextInt() throws IOException {
int ret = 0;
byte c = read();
while (c <= ' ') {
c = read();
}
boolean neg = (c == '-');
if (neg)
c = read();
do {
ret = ret * 10 + c - '0';
} while ((c = read()) >= '0' && c <= '9');
if (neg)
return -ret;
return ret;
}
private void fillBuffer() throws IOException {
bytesRead = din.read(buffer, bufferPointer = 0,
BUFFER_SIZE);
if (bytesRead == -1)
buffer[0] = -1;
}
private byte read() throws IOException {
if (bufferPointer == bytesRead)
fillBuffer();
return buffer[bufferPointer++];
}
}
public static void main(String[] args) throws IOException {
Reader sc = new Reader();
PrintWriter writer = new PrintWriter(System.out);
long INF = 1000000000000L;
while (true) {
int n = sc.nextInt(), m = sc.nextInt();
if (n == 0 && m == 0) {
writer.flush();
return;
}
Graph graph = new Graph(n*m);
boolean[][] graveyard = new boolean[n][m], wormhole = new boolean[n][m];
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++) {
graveyard[i][j] = false;
wormhole[i][j] = false;
}
int g = sc.nextInt();
while (g-- > 0)
graveyard[sc.nextInt()][sc.nextInt()] = true;
int h = sc.nextInt();
while (h-- > 0) {
int x = sc.nextInt(), y = sc.nextInt();
graph.connect(x+y*n,sc.nextInt()+sc.nextInt()*n,sc.nextInt());
wormhole[x][y] = true;
}
for (int i = 0; i < m; i++)
for (int j = 0; j < n; j++)
if (!wormhole[j][i] && !graveyard[j][i] && (i != m-1 || j != n-1)) { // not the exit
if (j > 0 && !graveyard[j-1][i])
graph.connect(i*n+j,i*n+(j-1),1); // left
if (j < n-1 && !graveyard[j+1][i])
graph.connect(i*n+j,i*n+(j+1),1); // right
if (i > 0 && !graveyard[j][i-1])
graph.connect(i*n+j,(i-1)*n+j,1); // up
if (i < m-1 && !graveyard[j][i+1])
graph.connect(i*n+j,(i+1)*n+j,1); // down
}
graph.doSSSP(0);
long sp = graph.D[n*m-1];
boolean never = false;
for (int i = 0; i < n*m; i++)
if (graph.D[i] == -INF) {
never = true;
break;
}
if (!never && sp == INF)
writer.println("Impossible");
else if (never)
writer.println("Never");
else
writer.println(sp);
}
}
}
class Graph {
public List<Triple> list;
public int numVertices;
public long[] D;
public boolean[] neg;
public long INF = 1000000000000L;
public Graph (int V) {
numVertices = V;
list = new ArrayList<Triple>();
}
public void connect (int a, int b, int w) { list.add(new Triple(a,b,w)); }
public void relax (int u, int v, int w) {
if (D[u] != INF && D[v] > D[u] + w) // if SP can be shortened
D[v] = D[u] + w; // relax this edge
}
public void doSSSP (int s) {
// Initialize
D = new long[numVertices];
neg = new boolean[numVertices];
for (int i = 0; i < numVertices; i++) {
D[i] = INF;
neg[i] = false;
}
D[s] = 0;
// Bellman-Ford's algorithm
for (int i = 0; i < numVertices-1; i++)
for (Triple edge : list)
relax(edge.first, edge.second, edge.third);
// Negative cycle check
boolean stillFound = true;
while (stillFound) {
stillFound = false;
for (Triple edge : list) {
if (D[edge.first] != INF && D[edge.second] > D[edge.first] + edge.third && !neg[edge.second]) {
D[edge.second] = -INF; // don't use Long.MAX_VALUE nor Integer.MAX_VALUE
neg[edge.second] = true;
stillFound = true;
}
}
}
}
}
class Triple {
public int first;
public int second;
public int third;
public Triple (int a, int b, int w) {
first = a;
second = b;
third = w;
}
}