【Leetcode】Clone Graph

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.
* struct UndirectedGraphNode {
*     int label;
*     vector<UndirectedGraphNode *> neighbors;
*     UndirectedGraphNode(int x) : label(x) {};
* };
*/
class Solution {
public:
UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
unordered_map<UndirectedGraphNode *, UndirectedGraphNode *> map;
if (node == nullptr) {
return nullptr;
}
return clone(node, map);
}
private:
UndirectedGraphNode *clone(UndirectedGraphNode *node,
unordered_map<UndirectedGraphNode *, UndirectedGraphNode *> &map) {
if (map.find(node) != map.end()) {
return map[node];
}
UndirectedGraphNode *new_node = new UndirectedGraphNode(node->label);
map[node] = new_node;
for (auto n : node->neighbors) {
new_node->neighbors.push_back(clone(n, map));
}
return new_node;
}
};

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