Leetcode 19. Remove Nth Node From End of List | | Leetcode 19. Remove Nth Node From End of List 文章作者:Tyan博客:noahsnail.com | CSDN | 简书 1. Description 2. Solution Version 1 123456789101112131415161718192021222324252627282930313233343536373839404142/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public: ListNode* removeNthFromEnd(ListNode* head, int n) { if(!head || !head->next) { return nullptr; } int number = 0; ListNode* current = head; while(current) { if(current->next) { number += 2; current = current->next->next; } else { number += 1; current = current->next; } } int target = number - n; if(target == 0) { return head->next; } ListNode* pre = head; current = head->next; int count = 1; while(count != target) { pre = current; current = current->next; count++; } pre->next = pre->next->next; return head; }}; Version 2 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public: ListNode* removeNthFromEnd(ListNode* head, int n) { if(!head || !head->next) { return nullptr; } int number = 0; int count = 0; ListNode* middle = head; ListNode* current = head; while(current) { count++; middle = middle->next; if(current->next) { number += 2; current = current->next->next; } else { number += 1; current = current->next; } } int target = number - n; if(target == 0) { return head->next; } ListNode* pre = nullptr; int index = 0; if(target > count) { index = count; current = middle; } else { current = head; } while(index != target) { pre = current; current = current->next; index++; } pre->next = pre->next->next; return head; }}; Version 3 1234567891011121314151617181920212223242526/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public: ListNode* removeNthFromEnd(ListNode* head, int n) { ListNode* new_head = new ListNode(0); new_head->next = head; ListNode* current = new_head; for(int i = 0; i < n + 1; i++) { current = current->next; } ListNode* pre = new_head; while(current) { current = current->next; pre = pre->next; } pre->next = pre->next->next; return new_head->next; }}; Reference https://leetcode.com/problems/remove-nth-node-from-end-of-list/description/ 如果有收获,可以请我喝杯咖啡! 赏 微信打赏 支付宝打赏