题解 | #链表中环的入口结点#
链表中环的入口结点
https://www.nowcoder.com/practice/253d2c59ec3e4bc68da16833f79a38e4
/*
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) :
val(x), next(NULL) {
}
};
*/
#include <unordered_set>
class Solution {
public:
ListNode* EntryNodeOfLoop(ListNode* pHead) {
unordered_set<ListNode*> ans;
while(pHead!=nullptr){
if(ans.count(pHead)){
return pHead;
}
ans.insert(pHead);
pHead=pHead->next;
}
return nullptr;
}
};
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