dsa-competitive-programming/leetcode/lc19/TwoPass.cpp

ListNode* removeNthFromEnd(ListNode* head, int n){
    if(head == nullptr) return head;
    ListNode* temp = head;
    int count = 0;
    while(temp!=nullptr) {
        count++;
        temp = temp->next;
    }
    if(n==count) {
        ListNode* newHead = head->next;
        delete head;
        return newHead;
    }
    temp = head;
    for(int i = 1; i<(count-n);i++){
        temp  = temp->next;
    }
    ListNode* nodeToDelete = temp->next;
    temp->next = nodeToDelete->next;
    delete nodeToDelete;

    return head;

}
//n == count is when removal node is head
//count-n just goes to one node before the removal node