1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
|
import java.util.*;
class Main {
static Map<Integer, List<Integer>> tree = new HashMap<>();
static {
tree.put(1, Arrays.asList(2, 3));
tree.put(3, Arrays.asList(4));
tree.put(4, Arrays.asList(5, 6));
}
public static void main(String[] args) {
System.out.println(distance(6, 1, 0));
System.out.println(distance(5, 1, 0));
System.out.println(distance(2, 1, 0));
System.out.println(distance(4, 1, 0));
}
public static Integer distance(int node, int root, int dist) {
if (root == node)
return dist;
if (tree.containsKey(root)) {
for (int child : tree.get(root)) {
Integer d = distance(node, child, dist + 1);
if (d != null)
return d;
}
}
return null;
}
}
|
