Given a undirected graph, a node and a target, return the nearest node to given node which value of it is target, return NULL if you can’t find.

There is a mapping store the nodes’ values in the given parameters.
2——3 5
\ | |
\ | |
\ | |
\ | |
1 –4
Give a node 1, target is 50

there a hash named values which is [3,4,10,50,50], represent:
Value of node 1 is 3
Value of node 2 is 4
Value of node 3 is 10
Value of node 4 is 50
Value of node 5 is 50

Return node 4

/** * Definition for graph node. * class UndirectedGraphNode { * int label; * ArrayList<UndirectedGraphNode> neighbors; * UndirectedGraphNode(int x) { * label = x; neighbors = new ArrayList<UndirectedGraphNode>(); * } * }; */
public class Solution {
    /** * @param graph a list of Undirected graph node * @param values a hash mapping, <UndirectedGraphNode, (int)value> * @param node an Undirected graph node * @param target an integer * @return the a node */
    public UndirectedGraphNode searchNode(ArrayList<UndirectedGraphNode> graph,
                                          Map<UndirectedGraphNode, Integer> values,
                                          UndirectedGraphNode node,
                                          int target) {
        Queue<UndirectedGraphNode> queue = new LinkedList<>();
        Set<UndirectedGraphNode> hash = new HashSet<>();
        queue.offer(node);
        hash.add(node);
        while (!queue.isEmpty()) {
            UndirectedGraphNode n = queue.poll();
            if (values.get(n) == target) {
                return n;
            }
            for (UndirectedGraphNode neighbor : n.neighbors) {
                if (!hash.contains(neighbor)) {
                    queue.offer(neighbor);
                    hash.add(neighbor);
                }
            }
        }
        return null;
    }
}