LinkedList 遍历

两个问题

1）如何遍历

2）如何design + 找中点 + reverse

key

• 小心不要丢head，小心不要丢any ListNode

• 小心null pointer exception

• trick，处理后面的先

• trick，先处理null，一个，甚至两个的corner case

• trick，注意是准备2个，还是3个linkedNode一起处理

遍历single LinkedList/ double

public void traversal(ListNode head) {
    if (head == null) {
        return;
    }
    ListNode cur = head;
    while (cur != null) {
        System.out.println(cur.value);
        cur = cur.next;
    }
    
    // alternative 写法
    //while (cur.next != null) {
    //    System.out.println(cur.value);
    //    cur = cur.next;
    //}
    //System.out.println(cur.value);

}

遍历circular LinkedList

public void traversal(ListNode head) {
    if (head == null) {
        return;
    }
    ListNode cur = head;
    while (cur.next != head) {
        System.out.printlin(cur.value);
        cur = cur.next;
    }
    System.out.println(cur.value);
}