2095. Delete the Middle Node of a Linked List

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problem

solution

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class Solution {
public:
    ListNode* deleteMiddle(ListNode* head) {
        if(!head->next) return nullptr;
        ListNode * pre = head, * slow = head, *fast = head;
        while(fast && fast->next){
            pre = slow;
            slow = slow->next;
            fast = fast->next->next;
        }
        pre->next = slow->next;
        return head;
    }
};s

analysis

  • time complexity O(n)
  • space complexity O(1)