题目：给定单向链表的头指针和一个结点指针，定义一个函数在O(1)时间删除该结点。
链表结点和函数的定义如下：

struct ListNode
{
    int m_nValue;
    ListNode* m_pNext;
}

void DeleteNode(ListNode** pListHead, ListNode* pToBeDeleted);

Java代码如下：

package demo;

public class Test12 {
    /**
     * 链表结点类
     */
    public static class ListNode {
        int value;
        ListNode next;
    }

    public static ListNode deleteNode(ListNode head, ListNode toBeDeleted) {
        // 如果输入参数有空值就返回头结点
        if(head == null || toBeDeleted == null) {
            return head;
        }
    
        // 如果删除头结点，则返回头结点的下一个结点
        if(head == toBeDeleted) {
            return head.next;
        }
    
        // 如果有多个结点，删除尾结点
        if(toBeDeleted.next == null) {
            // 从头结点开始遍历得到尾结点的前驱结点，然后删除
            ListNode tmp = head;
            while(tmp.next != toBeDeleted) {
                tmp = tmp.next;
            }
            tmp.next = null;
        } else {
            // 有多个结点，删除中间结点
            toBeDeleted.value = toBeDeleted.next.value;
            toBeDeleted.next = toBeDeleted.next.next;
        }
        return head;
    }

    /**
     * 打印链表中的元素值
     * @param head
     */
    public static void printList(ListNode head) {
        while(head != null) {
            System.out.print(head.value + "->");
            head = head.next;
        }
        System.out.println("null");
    }

    public static void main(String[] args) {
        ListNode head = new ListNode();
        head.value = 1;
        head.next = new ListNode();
        head.next.value = 2;
        ListNode middle = head.next.next = new ListNode();
        middle.value = 3;
        head.next.next.next = new ListNode();
        head.next.next.next.value = 4;
        ListNode tail = head.next.next.next.next = new ListNode();
        tail.value = 5;
    
        System.out.println("删除的结点为空：");
        printList(deleteNode(head, null));
        System.out.println("删除头结点：");
        printList(deleteNode(head, head));
        System.out.println("删除尾结点：");
        printList(deleteNode(head, tail));
        System.out.println("删除中间结点：");
        printList(deleteNode(head, middle));
    }
}

运行结果

来源：http://blog.csdn.net/derrantcm/article/details/45529213