add cloneGraph.cpp

Author: kamyu104

C++/cloneGraph.cpp

@@ -0,0 +1,37 @@
+// Time Complexity: O(n)
+// Space Complexity: O(n)
+
+/**
+ * Definition for undirected graph.
+ * struct UndirectedGraphNode {
+ *     int label;
+ *     vector<UndirectedGraphNode *> neighbors;
+ *     UndirectedGraphNode(int x) : label(x) {};
+ * };
+ */
+class Solution {
+    public:
+        UndirectedGraphNode *cloneGraph(UndirectedGraphNode *node) {
+            if(!node)
+                return nullptr;
+            unordered_map<const UndirectedGraphNode *, UndirectedGraphNode *> copied;
+            copied[node] = new UndirectedGraphNode(node->label);
+            queue<const UndirectedGraphNode *> q;
+            q.push(node);
+            while(!q.empty()) {
+                auto node = q.front();
+                q.pop();
+
+                for(auto n : node->neighbors) {
+                    if(copied.find(n) == copied.end()) {
+                        copied[n] = new UndirectedGraphNode(n->label);
+                        q.push(n);
+                    }
+
+                    copied[node]->neighbors.push_back(copied[n]);
+                }
+            }
+
+            return copied[node];
+        }
+};