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CloneGraph.cpp
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CloneGraph.cpp
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#include<unordered_map>
using namespace std;
// Definition for a Node.
struct Node {
int val;
vector<Node*> neighbors;
Node() {
val = 0;
neighbors = vector<Node*>();
}
Node(int _val) {
val = _val;
neighbors = vector<Node*>();
}
Node(int _val, vector<Node*> _neighbors) {
val = _val;
neighbors = _neighbors;
}
};
class CloneGraph {
public:
Node* cloneGraph(Node* node) {
// Base case: node is nullptr.
if (node == nullptr) return nullptr;
// Keep an unordered_set.
unordered_map<int, Node*> seen;
// Implement DFS
return cloneGraphDFS(node, seen);
}
Node* cloneGraphDFS(Node* node, unordered_map<int, Node*>& seen) {
// Base Case
if (node == nullptr) return nullptr;
// If node is already seen.
if (seen.find(node->val) != seen.end()) return seen[node->val];
// Building a new node.
Node* newNode = new Node(node->val);
seen[newNode->val] = newNode;
// If node is not seen.
for (int i = 0; i < node->neighbors.size(); ++i) {
newNode->neighbors.push_back(cloneGraphDFS(node->neighbors.at(i), seen));
}
// Return the newly created node.
return newNode;
}
};