Remove Linked List Elements(leetcode203)

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

Example:

Input:  1->2->6->3->4->5->6, val = 6
Output: 1->2->3->4->5

實現：

public static ListNode removeElements(ListNode head, int val) {

    ListNode temp = head;
    ListNode pre = null;
    while(null != temp) {
        if (temp.val == val) {

            if (null == pre) {
                head = temp.next;
            }else{
                pre.next = temp.next;
            }

        }else {
            pre = temp;
        }
        temp = temp.next;


    }
    return head;
}

測試一下：

int array[] = {1,2,6,3,4,5,6};
ListNode head = ListNode.buildeListNode(array);
ListNode.printListNode(head);
ListNode.printListNode(removeElements(head,6));

這裏寫點方法構建鏈表，和輸出

public static void printListNode(ListNode head) {
    List list = new ArrayList();
    ListNode temp = head;
    while(null != temp){
        list.add(temp.val);
        temp = temp.next;
    }
    System.out.println(list);
}

public static ListNode buildeListNode(int[] array) {
    ListNode head = null;
    //當前節點
    ListNode temp = null;
    for (int i = 0;i< array.length;i++){
        if(i == 0){
            head = new ListNode(array[i]);
            temp = head;
        }else{
            ListNode newNode = new ListNode(array[i]);
            temp.next = newNode;
            temp = newNode;
        }
    }
    return head;
}

git：https://github.com/woshiyexinjie/leetcode-xin/tree/master/src/main/java/com/helloxin/leetcode/algorithms