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remove_nth_last.cpp
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47 lines (37 loc) · 957 Bytes
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/*
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.
*/
/**
* 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 dummy(0);
dummy.next = head;
int k = 0;
ListNode *far = head;
ListNode *near = head;
ListNode *prev = &dummy;
while (k < n) {
far = far -> next;
k++;
}
while (far) {
far = far -> next;
near = near -> next;
prev = prev -> next;
}
prev -> next = near -> next;
delete[] near;
return dummy.next;
}
};