Create 2046.Sort-Linked-List-Already-Sorted-Using-Absolute-Values.cpp

Author: wisdompeak

Linked_List/2046.Sort-Linked-List-Already-Sorted-Using-Absolute-Values/2046.Sort-Linked-List-Already-Sorted-Using-Absolute-Values.cpp

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+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode() : val(0), next(nullptr) {}
+ *     ListNode(int x) : val(x), next(nullptr) {}
+ *     ListNode(int x, ListNode *next) : val(x), next(next) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode* sortLinkedList(ListNode* head) 
+    {
+
+        ListNode* pos = new ListNode(0);
+        ListNode* neg = new ListNode(0);
+        ListNode* h = head;
+        ListNode* p1 = pos;
+        ListNode* p2 = neg;
+        
+        while (h)
+        {
+            if (h->val>=0)
+            {
+                p1->next = h;
+                h = h->next;
+                p1 = p1->next;
+                                                
+            }
+            else
+            {
+                p2->next = h;
+                h = h->next;
+                p2 = p2->next;              
+            }
+        }
+        p1->next = NULL;
+        p2->next = NULL;
+        
+        pos = pos->next;
+        neg = neg->next;
+        
+        neg = reverseLinkedList(neg);
+        
+        if (neg)
+        {
+            h = neg;
+            while (h->next) h = h->next;
+            h->next = pos;            
+            return neg;
+        }
+        else
+            return pos;
+    }
+    
+    ListNode* reverseLinkedList(ListNode* head)
+    {
+        ListNode* cur = head;
+        ListNode* last = NULL;
+        ListNode* next = NULL;
+        while (cur!=NULL)
+        {
+            next = cur->next;
+            cur->next = last;
+            last = cur;
+            cur = next;
+        }
+        return last;
+    }
+};