add: 220606

cpp/2206/220606.cpp

@@ -0,0 +1,31 @@
+#include <unordered_set>
+
+struct ListNode {
+	int val;
+	ListNode* next;
+
+	explicit ListNode(int x, ListNode* n = nullptr) : val(x), next(n) {}
+
+	~ListNode() {
+		delete this->next;
+		this->next = nullptr;
+	}
+};
+
+/**
+ * 160. Intersection of Two Linked Lists
+ * Given the heads of two singly linked-lists headA and headB, return the node at which the two lists intersect. If the two linked lists have no intersection at all, return null.
+ */
+
+class Solution {
+public:
+	ListNode* getIntersectionNode(ListNode* headA, ListNode* headB) {
+		std::unordered_set<ListNode*> s;
+		for (auto* ptr = headA; ptr; ptr = ptr->next)
+			s.insert(ptr);
+		for (auto* ptr = headB; ptr; ptr = ptr->next)
+			if (s.count(ptr))
+				return ptr;
+		return nullptr;
+	}
+};