LeetCode:Partition List(java)

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本文详细解析了链表分区算法的实现，通过一个具体示例展示了如何将链表中的节点根据给定值进行分区，使得所有小于该值的节点位于大于等于该值的节点之前，同时保持各分区内的相对顺序不变。

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package LeetCode_LinkedList;

/**
 * 题目:
 *      Given a linked list and a value x, partition it such that all nodes less than x come before
 *      nodes greater than or equal to x.
 *      You should preserve the original relative order of the nodes in each of the two partitions.
 *      Example:
 *          Input: head = 1->4->3->2->5->2, x = 3
 *          Output: 1->2->2->4->3->5
 */
public class Partition_86_1012 {
    public ListNode Partition(ListNode head,int x ) {
        if (head == null) {
            return head;
        }

        ListNode head1 = new ListNode(-1);
        ListNode cur1 = head1;


        ListNode head2 = new ListNode(-1);
        ListNode cur2 = head2;

        ListNode temp = head;

        while (temp != null) {
            if (temp.val < x) {
                cur1.next = temp;
                cur1 = temp;
            } else {
                cur2.next = temp;
                cur2 = temp;
            }
            temp = temp.next;
        }

        cur2.next = null;
        cur1.next = head2.next;

        return head1.next;
    }
    public static void main(String[] args) {
        ListNode node1 = new ListNode(1);
        ListNode node2 = new ListNode(4);
        ListNode node3 = new ListNode(3);
        ListNode node4 = new ListNode(2);
        ListNode node5 = new ListNode(5);
        ListNode node6 = new ListNode(2);

        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;
        node5.next = node6;

        Partition_86_1012 test = new Partition_86_1012();
        ListNode result = test.Partition(node1,3);
        while (result != null) {
            System.out.print(result.val + " ");
            result = result.next;
        }
    }
}