//203. Remove Linked List Elements

#include<iostream>


using namespace std;
//Definition for singly-linked list.


struct ListNode{
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};


//LinkedList Test Helper Functions
ListNode* createLinkedList(int arr[], int n){


if (n == 0)
return NULL;


ListNode* head = new ListNode(arr[0]);
ListNode* curNode = head;
for (int i = 1; i < n; i++){
curNode->next = new ListNode(arr[i]);
curNode = curNode->next;
}


return head;
}


void printLinkedList(ListNode* head){

if (head == NULL){
cout << "NULL" << endl;
return;
}


ListNode* curNode = head;
while (curNode != NULL){
cout << curNode->val;
if (curNode->next != NULL)
cout << "->";
curNode = curNode->next;
}
cout << endl;

return;
}


void deleteLinkedList(ListNode* head){


ListNode* curNode = head;
while (curNode != NULL){
ListNode* delNode = curNode;
curNode = curNode->next;
delete delNode;
}


return;
}


//203. Remove Linked List Elements


class Solution{
public:
ListNode* removeElements(ListNode* head, int val){

//需要对头结点进行特殊处理
while (head != NULL && head->val == val){
ListNode* node = head;
head = head->next;
delete node;
}


if (head == NULL)
return head;


ListNode* cur = head;
while (cur->next != NULL){
if (cur->next->val == val){
ListNode* delNode = cur->next;
cur->next = delNode->next;
delete delNode;
}
else
cur = cur->next;
}


return head;
}


};


int main(){


int arr[] = { 1, 2, 6, 3, 4, 5, 6 };
int n = sizeof(arr) / sizeof(int);


ListNode* head = createLinkedList(arr, n);
printLinkedList(head);


Solution().removeElements(head, 6);
printLinkedList(head);


deleteLinkedList(head);


return 0;
}