LintCode: Remove Linked List Elements

C++

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    /**
     * @param head a ListNode
     * @param val an integer
     * @return a ListNode
     */
    ListNode *removeElements(ListNode *head, int val) {
        // Write your code here
        // Find the first non-Val node
        while ( head != NULL && head->val == val ) {
            head = head->next;
        }
        // If the head is NULL, return
        if ( head == NULL ) {
            return head;
        }
        // Remove the left val nodes
        ListNode *pre = head;
        ListNode *cur = pre->next;
        while ( cur != NULL ) {
            if ( cur->val != val ) {
                pre->next = cur;
                pre = pre->next;
            }
            cur = cur->next;
        }
        // In case of the tail has val node
        pre->next = cur;
        // return
        return head;
    }
};