Thursday, February 4, 2016

Remove Linked List Elements

Remove Linked List Elements

Remove all elements from a linked list of integers that have value val.

Example

Given 1->2->3->3->4->5->3, val = 3, you should return the list as 1->2->4->5


 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    /**
     * @param head a ListNode
     * @param val an integer
     * @return a ListNode
     */
    public ListNode removeElements(ListNode head, int val) {
        // Write your code here
        ListNode dummy = new ListNode(0);
        dummy.next = head;
        head = dummy;
        
        while (head.next != null) {
            if (head.next.val == val) {
                head.next= head.next.next;
            }
            else {
                head = head.next;
            }
        }
        return dummy.next;

    }
}

不用dummy
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    /**
     * @param head a ListNode
     * @param val an integer
     * @return a ListNode
     */
    public ListNode removeElements(ListNode head, int val) {
        // Write your code here
        ListNode cur = head;
        if(head == null) {
            return null;
        }
        
        while(cur.next != null) {
            if(cur.next.val == val) {
                cur.next = cur.next.next;
            }
            else {
                cur = cur.next;
            }
        }
        
        return (head.val == val)?head.next:head;
    }
}
Posted by at