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CloneGraph.java
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66 lines (64 loc) · 1.98 KB
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/**
* Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.
*
* OJ's undirected graph serialization:
* Nodes are labeled uniquely.
*
* We use # as a separator for each node, and , as a separator for node label and each neighbor of the node.
* As an example, consider the serialized graph {0,1,2#1,2#2,2}.
*
* The graph has a total of three nodes, and therefore contains three parts as separated by #.
*
* First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
* Second node is labeled as 1. Connect node 1 to node 2.
* Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.
* Visually, the graph looks like the following:
*
* 1
* / \
* / \
* 0 --- 2
* / \
* \_/
*/
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;
import java.util.Set;
public class CloneGraph {
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if (node == null)
return node;
Queue<UndirectedGraphNode> queue = new LinkedList<UndirectedGraphNode>();
queue.add(node);
Set<UndirectedGraphNode> visited = new HashSet<UndirectedGraphNode>();
Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();
while (!queue.isEmpty()) {
UndirectedGraphNode n = queue.remove();
if (visited.contains(n))
continue;
visited.add(n);
UndirectedGraphNode clone;
if (!map.containsKey(n)) {
clone = new UndirectedGraphNode(n.label);
map.put(n, clone);
} else {
clone = map.get(n);
}
for (UndirectedGraphNode child : n.neighbors) {
queue.add(child);
UndirectedGraphNode cloneChild;
if (!map.containsKey(child)) {
cloneChild = new UndirectedGraphNode(child.label);
map.put(child, cloneChild);
} else {
cloneChild = map.get(child);
}
clone.neighbors.add(cloneChild);
}
}
return map.get(node);
}
}