检查节点元素的总和是否等于给定的键值

给定一个整数k和一个链表，链表的每个节点都由一对整数变量first和second 组成，用于保存数据，以及一个指向链表中下一个节点的指针。任务是找出任何节点的数据变量之和是否等于k 。如果是，则打印Yes否则打印No 。

例子：

Input: (1, 2) -> (2, 3) -> (3, 4) -> (4, 5) -> NULL, k = 5 
Output: Yes 
For the second node, the sum of data variables is 2 + 3 = 5.

Input: (1, 2) -> (2, 3) -> (3, 4) -> (4, 5) -> NULL, k = 15 
Output: No 

方法：遍历整个链表，直到一个节点的元素之和等于key值。当节点元素的总和等于键值时，打印Yes 。如果不存在元素总和等于键值的节点，则打印No 。

下面是上述方法的实现：

C++

// C++ implementation of the approach
#include 
using namespace std;
 
// Represents node of the linked list
struct Node {
    int first;
    int second;
    Node* next;
};
 
// Insertion in linked list
void insert(Node** head, int f, int s)
{
    Node* ptr = *head;
    Node* temp = new Node();
    temp->first = f;
    temp->second = s;
    temp->next = NULL;
 
    if (*head == NULL)
        *head = temp;
    else {
        while (ptr->next != NULL)
            ptr = ptr->next;
 
        ptr->next = temp;
    }
}
 
// Function that returns true
// if the sum of element in a node = k
bool checkK(Node* head, int k)
{
 
    // Check every node of the linked list
    while (head != NULL) {
 
        // If sum of the data of the current node = k
        if ((head->first + head->second) == k)
            return true;
 
        // Get to next node in the list
        head = head->next;
    }
 
    // No matching node found
    return false;
}
// Driver code
int main()
{
    Node* head = NULL;
    insert(&head, 1, 2);
    insert(&head, 2, 3);
    insert(&head, 3, 4);
    insert(&head, 4, 5);
    int k = 5;
 
    if (checkK(head, k))
        cout << "Yes";
    else
        cout << "No";
 
    return 0;
}

Java

// Java implementation of the approach
class GfG {
 
    // Represents node of the linked list
    static class Node {
        int first;
        int second;
        Node next;
    }
    static Node head = null;
 
    // Insertion in linked list
    static void insert(int f, int s)
    {
        Node ptr = head;
        Node temp = new Node();
        temp.first = f;
        temp.second = s;
        temp.next = null;
 
        if (head == null)
            head = temp;
        else {
            while (ptr.next != null)
                ptr = ptr.next;
 
            ptr.next = temp;
        }
    }
 
    // Function that returns true
    // if the sum of element in a node = k
    static boolean checkK(Node head, int k)
    {
 
        // Check every node of the linked list
        while (head != null) {
 
            // If sum of the data of the current node = k
            if ((head.first + head.second) == k)
                return true;
 
            // Get to next node in the list
            head = head.next;
        }
 
        // No matching node found
        return false;
    }
    // Driver code
    public static void main(String[] args)
    {
        // Node* head = NULL;
        insert(1, 2);
        insert(2, 3);
        insert(3, 4);
        insert(4, 5);
        int k = 5;
 
        if (checkK(head, k) == true)
            System.out.println("Yes");
        else
            System.out.println("No");
    }
}
 
// This code is contributed by Prerna Saini

Python3

# Python3 implementation of the approach
  
# Represents node of the linked list
class Node:
     
    def __init__(self):
         
        self.first = 0
        self.second = 0
        self.next = None
 
# Insertion in linked list
def insert(head, f, s):
 
    ptr = head
    temp = Node()
    temp.first = f
    temp.second = s
    temp.next = None
  
    if (head == None):
        head = temp
    else:
        while (ptr.next != None):
            ptr = ptr.next
  
        ptr.next = temp
         
    return head
     
# Function that returns true
# if the sum of element in a node = k
def checkK(head, k):
 
    # Check every node of the linked list
    while (head != None):
  
        # If sum of the data of the current node = k
        if ((head.first + head.second) == k):
            return True
  
        # Get to next node in the list
        head = head.next
  
    # No matching node found
    return False
 
# Driver code
if __name__=='__main__':
     
    head = None
    head = insert(head, 1, 2)
    head = insert(head, 2, 3)
    head = insert(head, 3, 4)
    head = insert(head, 4, 5)
    k = 5
  
    if (checkK(head, k)):
        print("Yes")
    else:
        print("No")
  
# This code is contributed by rutvik_56

C#

using System;
 
// c# implementation of the approach
public class GfG {
 
    // Represents node of the linked list
    public class Node {
        public int first;
        public int second;
        public Node next;
    }
    public static Node head = null;
 
    // Insertion in linked list
    public static void insert(int f, int s)
    {
        Node ptr = head;
        Node temp = new Node();
        temp.first = f;
        temp.second = s;
        temp.next = null;
 
        if (head == null) {
            head = temp;
        }
        else {
            while (ptr.next != null) {
                ptr = ptr.next;
            }
 
            ptr.next = temp;
        }
    }
 
    // Function that returns true
    // if the sum of element in a node = k
    public static bool checkK(Node head, int k)
    {
 
        // Check every node of the linked list
        while (head != null) {
 
            // If sum of the data of the current node = k
            if ((head.first + head.second) == k) {
                return true;
            }
 
            // Get to next node in the list
            head = head.next;
        }
 
        // No matching node found
        return false;
    }
    // Driver code
    public static void Main(string[] args)
    {
        // Node* head = NULL;
        insert(1, 2);
        insert(2, 3);
        insert(3, 4);
        insert(4, 5);
        int k = 5;
 
        if (checkK(head, k) == true) {
            Console.WriteLine("Yes");
        }
        else {
            Console.WriteLine("No");
        }
    }
}

Javascript

 
// Javascript implementation of the approach
 
// Structure of a node of linked list
class Node {
        constructor() {
                this.first = 0;
                this.second = 0;
                this.next = null;
             }
        }
         
// Insertion in linked list
function insert( f,  s)
{
    var ptr = head;
    var temp = new Node();
    temp.first = f;
    temp.second = s;
    temp.next = null;
 
    if (head == null)
        head = temp;
    else {
        while (ptr.next != null)
            ptr = ptr.next;
 
        ptr.next = temp;
    }
}
 
// Function that returns true
// if the sum of element in a node = k
function checkK( head,  k)
{
 
    // Check every node of the linked list
    while (head != null) {
 
        // If sum of the data of the current node = k
        if ((head.first + head.second) == k)
            return true;
 
        // Get to next node in the list
        head = head.next;
    }
 
    // No matching node found
    return false;
}
 
// Driver Code
 
var head = null;
insert(1, 2);
insert(2, 3);
insert(3, 4);
insert(4, 5);
let k = 5;
 
if (checkK(head, k) == true)
    document.write("Yes");
else
    document.write("No");
 
// This code is contributed by jana_sayantn.

输出：

Yes

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