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CloneGraph.java
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CloneGraph.java
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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
/ \
\_/
*/
/**
* Definition for undirected graph.
* class UndirectedGraphNode {
* int label;
* List<UndirectedGraphNode> neighbors;
* UndirectedGraphNode(int x) { label = x; neighbors = new ArrayList<UndirectedGraphNode>(); }
* };
*/
class CloneGraph {
//BFS
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if(node == null)
return null;
Queue<UndirectedGraphNode> queue = new LinkedList<UndirectedGraphNode>();
Map<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();
UndirectedGraphNode newHead = new UndirectedGraphNode(node.label);
queue.add(node);
map.put(node, newHead);
while(!queue.isEmpty()) {
UndirectedGraphNode curr = queue.pop();
List<UndirectedGraphNode> currNeighbors = curr.neighbors;
for(UndirectedGraphNode aNeighbors : currNeighbors) {
if(!map.containsKey(aNeighbors)) {
UndirectedGraphNode copy = new UndirectedGraphNode(aNeighbors.label);
map.put(aNeighbors, copy);
map.get(curr).neighbors.add(copy);
queue.add(aNeighbors);
}
//针对self-cycle的情况
else {
map.get(curr).neighbors.add(map.get(aNeighbors));
}
}
}
return newHead;
}
//DFS, recursive
public UndirectedGraphNode cloneGraphDFS(UndirectedGraphNode node) {
if(node == null)
return null;
UndirectedGraphNode newHead = new UndirectedGraphNode(node.label);
HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();
map.put(node, newHead);
DFS(node, map);
return newHead;
}
public void DFS(UndirectedGraphNode node, HashMap<UndirectedGraphNode, UndirectedGraphNode> map) {
if(node == null)
return;
for(UndirectedGraphNode aNeighbors : node.neighbors) {
if(!map.containsKey(aNeighbors)) {
UndirectedGraphNode copy = new UndirectedGraphNode(aNeighbors.label);
map.put(aNeighbors, copy);
DFS(aNeighbors, map);
}
map.get(node).neighbors.add(map.get(aNeighbors));
}
}
//DFS, stack
public UndirectedGraphNode cloneGraph(UndirectedGraphNode node) {
if(node == null)
return null;
UndirectedGraphNode newHead = new UndirectedGraphNode(node.label);
HashMap<UndirectedGraphNode, UndirectedGraphNode> map = new HashMap<UndirectedGraphNode, UndirectedGraphNode>();
LinkedList<UndirectedGraphNode> stack = new LinkedList<UndirectedGraphNode>();
map.put(node, newHead);
stack.push(node);
while(!stack.isEmpty()) {
UndirectedGraphNode curr = stack.pop();
for(UndirectedGraphNode aNeighbors : curr.neighbors) {
if(!map.containsKey(aNeighbors)) {
stack.push(aNeighbors);
UndirectedGraphNode copy = new UndirectedGraphNode(aNeighbors.label);
map.put(aNeighbors, copy);
}
map.get(curr).neighbors.add(map.get(aNeighbors));
}
}
return newHead;
}
}