Question

请考虑我的代码，以便在特定位置插入节点，假设链表已排序：

package datastructures;
public class Link {
    int data;
    Link next;

    public Link(int d){
        this.data = d;
    }

    public void displayLink(){
        System.out.println(data + " ");
    }

    public static class LinkList {
        Link first;

        public void insertFirst(int x) {
            Link newLink = new Link(x);
            newLink.next = first;
            first = newLink;
        }

        public Link deleteFirst() {
            Link temp = first;
            first = first.next;
            return temp;
        }

        public void displayList() {
            Link current = first;
            while (current != null) {
               current.displayLink();
               current = current.next;
            }
        }

        public void insertNodeAtParticularLocation(int x){
            Link previous = first;
            Link current = first.next;

            if (first == null){
                // if node doesn't exist in the 
                // linkedlist then just create a new node
                Link newNode = new Link(x);
            } else if (x < first.data) {
                // Else if the value that needs to be inserted
                // is less than the first element, then insert 
                // it at the very beginning

                Link newNode = new Link(x);
                newNode.next = first;
                first = newNode;
            } else {
                while(current.data > x){ // In case of21,22,23,27 ; If x = 24 , current should stop at 27
                    previous = current;
                    current = current.next;
                    Link newNode = new Link(x);
                    previous.next = newNode;
                    newNode.next = current;
                }
            }
        }
    }


    public static void main(String[] args) {

        LinkList addElements = new LinkList();

        addElements.insertFirst(21);
        addElements.insertFirst(22);
        addElements.insertFirst(23);
        addElements.insertFirst(27);
        addElements.insertFirst(29);

        System.out.println("Display Original Elements");

        addElements.displayList();

        addElements.insertNodeAtParticularLocation(24);

        System.out.println("Display Elements after First Modification");

        addElements.displayList();
    }
}

我的insertNodeAtParticularLocation()方法存在一些问题。

问题＃1：

当我尝试添加24时，它仍然会添加到列表的末尾，而不是添加到应该位于值为23的节点之后的指定位置。

问题＃2：

另外，我尝试添加另一个值10，我希望在开头添加它，但是它覆盖了最后一个27的元素，并添加了它的位置。请让我知道我做错了什么。

Answer 1

存在多个问题：

insertFirst将先前插入的元素推送到后面。如果要在main中使用insertFirst，则需要颠倒顺序：

addElements.insertFirst(29);
addElements.insertFirst(27);
addElements.insertFirst(23);
addElements.insertFirst(22);
addElements.insertFirst(21);

insertNodeAtParticularLocation存在一些问题：

第一个== null的情况不起作用，因为它没有先分配
while循环看起来可能会在错误的位置插入多个元素

我按如下方式写insertNodeAtParticularLocation：

    public void insertNodeAtParticularLocation(int x) {
        if (first == null || x < first.data) {
            // if the value that needs to be inserted
            // is less than the first element, or it does not exist,
            // then insert it at the very beginning
            insertFirst(x);
        } else {
            Link previous = first;
            Link current = first.next;
            while(current != null && current.data > x) {
                previous = current;
                current = current.next;
            }
            Link newNode = new Link(x);
            previous.next = newNode;
            newNode.next = current;
        }
    }

在特定位置插入节点时的逻辑错误

1 个答案: