86. Partition List - Medium

前往題目

想法

• 循環兩次，一次組小於x的，一次組大於等於x的

思路

其實一次就好，一起組

1. 宣告兩個新的list
2. 走訪每個ListNode，< x的放一組，>= x的放一組
3. 兩組連起來

Code

class Solution {
    public ListNode partition(ListNode head, int x) {
        ListNode left = new ListNode(-101), right = new ListNode(-101);
        ListNode leftHead = left, rightHead = right;

        // Go through all the elements
        while (head != null) {
            if (head.val < x) {
                left.next = head;
                left = left.next;
            } else {
                right.next = head;
                right = right.next;
            }
            // Move to the next element
            head = head.next;
        }

        // Connect 2 lists
        left.next = rightHead.next;
        right.next = null;
        return leftHead.next;
    }
}