Problem 160

Author: ZQKC

160.Intersection of Two Linked Lists.cpp

@@ -0,0 +1,39 @@
+/**
+ * Definition for singly-linked list.
+ * struct ListNode {
+ *     int val;
+ *     ListNode *next;
+ *     ListNode(int x) : val(x), next(NULL) {}
+ * };
+ */
+class Solution {
+public:
+    ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
+        if (headA == NULL || headB == NULL)
+            return NULL;
+
+        ListNode *pA = headA;
+        while (pA->next != NULL) 
+            pA = pA ->next;
+        pA -> next = headA;
+        
+        ListNode *pB_s1 = headB, *pB_s2 = headB;
+        while (1){
+            pB_s1 = pB_s1->next != NULL ? pB_s1->next: NULL;
+            pB_s2 = pB_s2->next != NULL && pB_s2->next->next != NULL ? pB_s2->next->next: NULL;
+            if (pB_s1 == NULL || pB_s2 == NULL) {
+                pA -> next = NULL;
+                return NULL;
+            }
+            if (pB_s1 == pB_s2) 
+                break;
+        }
+        ListNode *pB = headB;
+        while (pB != pB_s1){
+            pB = pB->next;
+            pB_s1 = pB_s1->next;
+        }
+        pA -> next = NULL;
+        return pB_s1;
+    }
+};