我想在給定起點和終點的2d數組上實現BFS。我試着在網格上給出我的函數兩點,但它返回一個空數組,意味着沒有路徑。BFS不返回路徑
有人可以請指出我哪裏錯了,如果可能幫助我糾正我的錯誤?謝謝。
public Point[] bfs2(Point start, Point end) {
boolean[][] visited = new boolean[50][50];
for (int i = 0; i < visited.length; i++)
for(int j = 0; j < visited.length; j++)
visited[i][j] = false;
visited[start.getX()][start.getY()] = true;
LinkedList<Point> path = new LinkedList<>();
Queue<Point> q = new LinkedList<>();
q.add(start);
while (!q.isEmpty()) {
Point next = q.remove(); //i think the error is here
Point[] neighbours = next.getNeighbours();
path.add(next);
if (next.getX() == end.getX() && next.getY() == end.getY())
break;
else if (!visited[next.getX()][next.getY()]) {
for (Point neighbour : neighbours) {
if (!visited[neighbour.getX()][neighbour.getY()]) {
q.add(neighbour);
}
visited[neighbour.getX()][neighbour.getY()] = true;
}
}
}
Point current = path.removeLast();
ArrayList<Point> v = new ArrayList<>();
while (current.getX() != start.getX() || current.getY() != start.getY()) {
v.add(current);
current = path.removeLast();
}
return v.toArray(new Point[v.size()]);
}
編輯:
Point current=q.peek();
ArrayList<Point> v=new ArrayList<>();
if(start.getX()==end.getX() && start.getY()==end.getY()) return new Point[0];
while(current.getX()!=start.getX() || current.getY()!=start.getY()){
v.add(current);
current=current.parent;
}
return v.toArray(new Point[v.size()]);
任何原因爲最後7行復雜的代碼,而不是一個簡單的'Collections.reverse(路徑);'? –
請同時發佈您對「Point」的定義。更好的是,使它成爲一個MCVE(http://stackoverflow.com/help/mcve) –
(將'visited'的元素初始化爲'false'是多餘的。) – greybeard