Create Merge Two Sorted Lists.cpp

Author: daizhenyang

Merge Two Sorted Lists.cpp

@@ -0,0 +1,73 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode(int x) : val(x), next(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
+        // Start typing your C/C++ solution below
+        // DO NOT write int main() function
+        ListNode *p1=l1,*p2=l2;
+        ListNode *head=NULL,*ptr=NULL;
+        while (p1&&p2)
+        {
+            if (p1->val<p2->val)
+            {
+                if (!head)
+                {
+                    head=ptr=p1;
+                }
+                else 
+                {
+                    ptr->next=p1;
+                    ptr=p1;
+                }
+                p1=p1->next;
+            }
+            else 
+            {
+                if (!head)
+                {
+                    head=ptr=p2;
+                }
+                else 
+                {
+                    ptr->next=p2;
+                    ptr=p2;
+                }
+                p2=p2->next;
+            }
+        }
+        while (p1)
+        {
+            if (!head)
+            {
+                head=ptr=p1;
+            }
+            else 
+            {
+                ptr->next=p1;
+                ptr=p1;
+            }
+            p1=p1->next;
+        }
+        while (p2)
+        {
+            if (!head)
+            {
+                head=ptr=p2;
+            }
+            else 
+            {
+                ptr->next=p2;
+                ptr=p2;
+            }
+            p2=p2->next;
+        }
+        return head;
+    }
+};