week 3

hj/week3/CopyLinkedListWithRandomPointer.cpp

@@ -0,0 +1,40 @@
+/*
+// Definition for a Node.
+class Node {
+public:
+    int val;
+    Node* next;
+    Node* random;
+
+    Node(int _val) {
+        val = _val;
+        next = NULL;
+        random = NULL;
+    }
+};
+*/
+
+class Solution {
+public:
+    Node* copyRandomList(Node* head) {
+        if (!head) return nullptr;
+
+        unordered_map<Node*, Node*> um;
+
+        Node* crnt = head;
+        while (crnt) {
+            Node* node = new Node(crnt->val);
+            um[crnt] = node;
+            crnt = crnt->next;
+        }
+
+        crnt = head;
+        while (crnt) {
+            um[crnt]->next = um[crnt->next];
+            um[crnt]->random = um[crnt->random];
+            crnt = crnt->next;
+        }
+
+        return um[head];
+    }
+};