Merge pull request neetcode-gh#1325 from MHamiid/patch-3

Ahmad-A0 · web-flow · commit 49d874aa4751 · 2022-11-02T22:30:57.000Z
Add 138-Copy-List-with-Random-Pointer.c
diff --git a/c/138-Copy-List-with-Random-Pointer.c b/c/138-Copy-List-with-Random-Pointer.c
@@ -0,0 +1,89 @@
+/**
+ * Definition for a Node.
+ * struct Node {
+ *     int val;
+ *     struct Node *next;
+ *     struct Node *random;
+ * };
+ */
+
+/*
+    Time: O(n)
+    Space: O(1)
+*/
+
+typedef struct Node Node;
+struct Node* copyRandomList(struct Node* head) {
+    
+	    if(head == NULL)
+        {
+            return NULL;
+        }
+        
+        /**
+         * Insert each new node after each original node 
+         */
+        Node* curr = head;
+        while(curr)
+        {
+            // Create the new node
+            Node* newNode = (Node*)malloc(sizeof(Node));
+            newNode->val = curr->val;
+            
+            // Insert new node after the original node
+            newNode->next = curr->next;
+            curr->next = newNode;
+            
+            // Move curr to the next original node
+            curr = curr->next->next;
+        }
+        
+        
+        /**
+         * Add the random node for each new node 
+         */
+        curr = head;
+        Node* newNode = NULL;
+        while(curr)
+        {
+            // The new node is the next node to the original node
+            newNode = curr->next;
+
+            if(curr->random)
+            {
+                newNode->random = curr->random->next;
+            }
+            else
+            {
+                newNode->random = NULL;
+            }
+            
+            // Move curr to the next original node
+            curr = curr->next->next;
+        }
+        
+        /**
+         * Separate the original nodes list from the new nodes list  
+         */
+        Node* originalList = head;
+        Node* copiedList = head->next;
+        Node* copiedListHead = head->next;
+        while(originalList)
+        {
+            originalList->next = originalList->next->next;
+            if(copiedList->next)
+            {
+                copiedList->next = copiedList->next->next;
+            }
+            else
+            {
+                copiedList->next = NULL;
+            }
+            
+            originalList = originalList->next;
+            copiedList = copiedList->next;
+        }
+        
+       
+        return copiedListHead;
+}
