Create 138. Copy List with random pointer

Here is the solution in C++ without using mapping

Author: SjxSubham

138. Copy List with random pointer

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+// Here is the solution of this question without using map 
+// It's is much optimized  
+
+solution in C++
+
+class Solution {
+public:
+  Node* copyRandomList(Node* head) {
+       if(!head) return 0;
+       // step 1: clone a -> a'
+       Node* it = head;
+       while(it){
+           Node*clonedNode = new Node(it->val);
+           clonedNode->next = it->next;
+           it->next = clonedNode;
+           it = it->next->next;
+
+       }
+       //step 2: assign random links of A with the help of random pouinter
+        it = head;
+        while(it){
+            Node*clonedNode = it->next;
+            clonedNode->random = it->random ? it->random->next : nullptr;
+            it = it->next->next;
+        }
+        //step 3: detatch A from A
+        it = head;
+        Node*clonedHead = it->next;
+        while(it){
+            Node*clonedNode = it->next;
+            it->next = it->next->next;
+            if(clonedNode->next){
+                clonedNode->next = clonedNode->next->next;
+
+            }
+            it = it->next;
+        }
+        return clonedHead;
+    }
+};