leetcode:Remove Nth Node From End of List
Given a linked list, remove the nth node from the end of list and return its head.
For example,
Given linked list: 1->2->3->4->5, and n = 2. After removing the second node from the end, the linked list becomes 1->2->3->5.
Note:
Given n will always be valid.
Try to do this in one pass.
算法:
1 准备两个指针first, second
2 先让fisrt走n步
3 让fisrt和second同一时候走直到first遇到结尾
4 要用一个temp指针来记录second前一个node。用来删除second用。
/** * 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 *first = head, *second = head; ListNode *temp = second; for(int i = 0; i < n; i++) { first = first -> next; } while(first) { first = first -> next; temp = second; second = second -> next; } if(second == head) { head = head -> next; } else { temp -> next = second -> next; } return head; } };