/* struct ListNode { int val; struct ListNode *next; ListNode(int x) : val(x), next(NULL) { } }; */ class Solution { public: ListNode* EntryNodeOfLoop(ListNode* pHead) { unordered_map<ListNode*, int> hash; int i = 0; while (pHead != NULL) { if (hash.find(pHead) != hash.end()) { return pHead; }...