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📜  删除左侧具有较小值的链表节点

📅  最后修改于: 2022-05-13 01:57:05.727000             🧑  作者: Mango

删除左侧具有较小值的链表节点

给定一个单链表,任务是删除左侧具有较小值的所有节点。
例子:

Input: 12->15->10->11->5->6->2->3
Output: Modified Linked List = 12 -> 10 -> 5 -> 2 

Input: 25->15->6->48->12->5->16->14
Output: Modified Linked List = 25 -> 15 -> 6 -> 5   

方法:

  1. 用头节点初始化一个变量最大值
  2. 遍历列表。
  3. 检查下一个节点是否小于 max_node。如果是,则移动到下一个节点。
  4. 否则,如果不是,则更新 max_node 的值并删除下一个节点。

以下是上述方法的实现:

C++
// C++ implementation of above approach
#include 
using namespace std;
 
// Structure of a linked list node
struct Node {
    int data;
    struct Node* next;
};
 
// Function to Delete nodes which have
// greater value node(s) on right side
void delNodes(struct Node* head)
{
    struct Node* current = head;
 
    // Initialize max
    struct Node* maxnode = head;
    struct Node* temp;
 
    while (current != NULL && current->next != NULL) {
 
        // If current is greater than max,
        // then update max and move current
        if (current->next->data <= maxnode->data) {
            current = current->next;
            maxnode = current;
        }
 
        // If current is smaller than max, then delete current
        else {
            temp = current->next;
            current->next = temp->next;
            free(temp);
        }
    }
}
 
/* Utility function to insert a node at the beginning */
void push(struct Node** head_ref, int new_data)
{
    struct Node* new_node = new Node;
    new_node->data = new_data;
    new_node->next = *head_ref;
    *head_ref = new_node;
}
 
/* Utility function to print a linked list */
void printList(struct Node* head)
{
    while (head != NULL) {
        cout << head->data << " ";
        head = head->next;
    }
    cout << endl;
}
 
/* Driver program to test above functions */
int main()
{
    struct Node* head = NULL;
 
    /* Create following linked list
    12->15->10->11->5->6->2->3 */
    push(&head, 3);
    push(&head, 2);
    push(&head, 6);
    push(&head, 5);
    push(&head, 11);
    push(&head, 10);
    push(&head, 15);
    push(&head, 12);
 
    printf("Given Linked List: ");
    printList(head);
 
    delNodes(head);
 
    printf("\nModified Linked List: ");
    printList(head);
 
    return 0;
}


Java
// Java implementation of above approach
class Solution
{
 
// Structure of a linked list node
static class Node
{
    int data;
    Node next;
};
 
// Function to Delete nodes which have
// greater value node(s) on right side
static Node delNodes(Node head)
{
    Node current = head;
 
    // Initialize max
    Node maxnode = head;
    Node temp;
 
    while (current != null && current.next != null)
    {
 
        // If current is lesser than max,
        // then update max and move current
        if (current.next.data <= maxnode.data)
        {
            current = current.next;
            maxnode = current;
        }
 
        // If current is greater than max, then delete current
        else
        {
            temp = current.next;
            current.next = temp.next;
        }
    }
    return head;
}
 
 
// Utility function to insert a node at the beginning /
static Node push(Node head_ref, int new_data)
{
    Node new_node = new Node();
    new_node.data = new_data;
    new_node.next = head_ref;
    head_ref = new_node;
    return head_ref;
}
 
// Utility function to print a linked list /
static Node printList(Node head)
{
    while (head != null)
    {
        System.out.print( head.data + " ");
        head = head.next;
    }
    System.out.println();
    return head;
}
 
// Driver program to test above functions /
public static void main(String args[])
{
    Node head = null;
 
    /* Create following linked list
    12->15->10->11->5->6->2->3 */
    head=push(head, 3);
    head=push(head, 2);
    head=push(head, 6);
    head=push(head, 5);
    head=push(head, 11);
    head=push(head, 10);
    head=push(head, 15);
    head=push(head, 12);
 
    System.out.printf("Given Linked List \n");
    printList(head);
 
    head=delNodes(head);
 
    System.out.printf("Modified Linked List \n");
    printList(head);
}
}
 
// This code is contributed by Arnab Kundu


Python3
# Python implementation of above approach
import math
 
# Structure of a linked list node
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None
 
# Function to Delete nodes which have
# greater value node(s) on right side
def delNodes(head):
    current = head
 
    # Initialize max
    maxnode = head
    temp = None
 
    while (current != None and current.next != None):
 
        # If current is greater than max,
        # then update max and move current
        if (current.next.data <= maxnode.data):
            current = current.next
            maxnode = current
         
        # If current is smaller than max,
        # then delete current
        else:
            temp = current.next
            current.next = temp.next
            #free(temp)
     
# Utility function to insert a node at the beginning
def push(head_ref, new_data):
    new_node = Node(new_data)
    new_node.data = new_data
    new_node.next = head_ref
    head_ref = new_node
    return head_ref
 
# Utility function to print a linked list
def printList(head):
    while (head != None) :
        print(head.data, end = " ")
        head = head.next
    print()
     
# Driver Code
if __name__=='__main__':
    head = None
 
    # Create following linked list
    # 12.15.10.11.5.6.2.3
    head = push(head, 3)
    head = push(head, 2)
    head = push(head, 6)
    head = push(head, 5)
    head = push(head, 11)
    head = push(head, 10)
    head = push(head, 15)
    head = push(head, 12)
 
    print("Given Linked List: ", end = "")
    printList(head)
 
    delNodes(head)
 
    print("\nModified Linked List: ", end = "")
    printList(head)
 
# This code is contributed by AbhiThakur


C#
// C# implementation of the above approach:
using System;
class GFG
{
 
// Structure of a linked list node
public class Node
{
    public int data;
    public Node next;
};
 
// Function to Delete nodes which have
// greater value node(s) on right side
static Node delNodes(Node head)
{
    Node current = head;
 
    // Initialize max
    Node maxnode = head;
    Node temp;
 
    while (current != null &&
           current.next != null)
    {
 
        // If current is lesser than max,
        // then update max and move current
        if (current.next.data <= maxnode.data)
        {
            current = current.next;
            maxnode = current;
        }
 
        // If current is greater than max,
        // then delete current
        else
        {
            temp = current.next;
            current.next = temp.next;
        }
    }
    return head;
}
 
// Utility function to insert
// a node at the beginning
static Node push(Node head_ref,
                 int new_data)
{
    Node new_node = new Node();
    new_node.data = new_data;
    new_node.next = head_ref;
    head_ref = new_node;
    return head_ref;
}
 
// Utility function to print a linked list
static Node printList(Node head)
{
    while (head != null)
    {
        Console.Write(head.data + " ");
        head = head.next;
    }
    Console.WriteLine();
    return head;
}
 
// Driver Code
public static void Main(String []args)
{
    Node head = null;
 
    /* Create following linked list
    12->15->10->11->5->6->2->3 */
    head = push(head, 3);
    head = push(head, 2);
    head = push(head, 6);
    head = push(head, 5);
    head = push(head, 11);
    head = push(head, 10);
    head = push(head, 15);
    head = push(head, 12);
 
    Console.Write("Given Linked List \n");
    printList(head);
 
    head = delNodes(head);
 
    Console.Write("Modified Linked List \n");
    printList(head);
}
}
 
// This code is contributed by PrinciRaj1992


Javascript


输出:
Given Linked List: 12 15 10 11 5 6 2 3 

Modified Linked List: 12 10 5 2

时间复杂度: O(N),其中 N 是节点的总数。

辅助空间: O(1)