// first solution, a traversal number length, connected end to end and then, once again traversed
class Solution {
public:
ListNode removeNthFromEnd * (* ListNode head, n-int) {
ListNode TEM * = head;
int len = 0;
the while ( tem-> next) {// this is the true length of the length obtained -1
TEM TEM- => Next;
len ++;
}
IF (len == 0) return NULL;
IF (len ==. 1) {
IF (n-== . 1) {
head-> Next = NULL;
}
the else head = head-> Next;
return head;
}
TEM-> Next = head; // connected end to end
ListNode * tail = tem;
for (int i = 0; i <len-n + 1; i ++) {// departing from the last node, until the front reaches a node to be deleted; if you want to delete the node is the header, does not move
= TEM- TEM> Next;
}
ListNode Trash * = TEM-> Next; // To delete a node
tail-> next = NULL; // if you want to delete the last, if not the penultimate sentence and will a ring header connected
TEM-> Next = trash-> Next;
IF (Trash == head) head = head-> Next;
tail-> Next = NULL;
return head;
}
};
// The above classification is very difficult, and in fact, two pass, completely unnecessary
// special case to avoid trouble free and involved head and tail, and good use of the method is an empty list head plus the Node
class Solution {
public :
ListNode removeNthFromEnd * (* ListNode head, n-int) {
ListNode dummy = new new ListNode * (0);
dummy-> Next = head;
ListNode head * = R & lt;
int len = 0;
the while (R & lt) {
R & lt R- = > Next;
len ++;
}
R & lt dummy =;
for (int I = 0; I <-n-len; I ++) {
R & lt = R-> Next;
}
R-> Next = R-> next-> Next;
return dummy- > Next;
}
};
// Solution 3, made by traversing the two pointers, a first faster than the second n nodes, arrive a ranking when the tail, before the second is to delete a node.
{Solution class
public:
ListNode removeNthFromEnd * (* ListNode head, n-int) {
ListNode dummy = new new ListNode * (0);
dummy-> Next = head;
ListNode dummy = F *, S * = dummy;
for (int I = 0; I <n-; I ++) {
F = F-> Next;
}
the while (F-> Next) {
F = F-> Next;
S = S-> Next;
}
S-> Next = S-> next- > Next;
return dummy-> Next;
}
};