Add C++ implementation

Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>

Author: begeekmyfriend

0160_intersection_of_two_linked_list/intersection.c

@@ -9,23 +9,27 @@ struct ListNode {
 
 static struct ListNode *getIntersectionNode(struct ListNode *headA, struct ListNode *headB)
 {
+    if (headA == NULL || headB == NULL) {
+        return NULL;
+    }
+
     struct ListNode *p;
     for (p = headA; p->next != NULL; p = p->next) {}
     p->next = headB;
 
-    bool first = true;
-    struct ListNode *p0, *p1;
-    for (p0 = headA, p1 = headA; p1 != NULL && p1->next != NULL; p0 = p0->next, p1 = p1->next->next) {
-        if (p0 == p1 && !first) {
-            p0 = headA;
-            while (p0 != p1) {
-                p0 = p0->next;
-                p1 = p1->next;
+    struct ListNode *slow = headA, *fast = headA;
+    while (fast != NULL && fast->next != NULL) {
+        slow = slow->next;
+        fast = fast->next->next;
+        if (slow == fast) {
+            slow = headA;
+            while (slow != fast) {
+                slow = slow->next;
+                fast = fast->next;
             }
             p->next = NULL;
-            return p0;
+            return slow;
         }
-        first = false;
     }
 
     p->next = NULL;

0160_intersection_of_two_linked_list/intersection.cc

@@ -0,0 +1,44 @@
+#include <stdc++.h>
+
+using namespace std;
+
+/**
+ * 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) {
+        int lenA = getListLength(headA);
+        int lenB = getListLength(headB);
+        if (lenA > lenB) {
+            for (int i = 0; i < lenA - lenB; i++) {
+                headA = headA->next;
+            }
+        } else {
+            for (int i = 0; i < lenB - lenA; i++) {
+                headB = headB->next;
+            }
+        }
+
+        while (headA != nullptr && headB != nullptr && headA != headB) {
+            headA = headA->next;
+            headB = headB->next;
+        }
+
+        return headA;
+    }
+private:
+    int getListLength(ListNode *h) {
+        int len = 0;
+        while (h != nullptr) {
+            len++;
+            h = h->next;
+        }
+        return len;
+    }
+};