题解 | #链表中环的入口结点#

struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
        val(x), next(NULL) {
    }
};
*/
class Solution {
public:
    ListNode* EntryNodeOfLoop(ListNode* pHead) {
        int a[10005]={0};
        while(pHead){
            if(!a[pHead->val])
               a[pHead->val]=1;
            else return pHead;
            pHead=pHead->next;
        }
        return NULL;
            
    
    }
};