给定一个包含N个节点的循环单链接列表，任务是从列表中删除所有节点，其中包含数字和为偶数的元素。
例子：
Input: CLL = 9 -> 11 -> 34 -> 6 -> 13 -> 21
Output: 9 -> 34 -> 21
Explanation:
The circular singly linked list contains :
9 -> 9
11 -> 1 + 1 = 2
34 -> 3 + 4 = 7
6 -> 6
13 -> 1 + 3 = 4
21 -> 2 + 1 = 3
Here, digit sum for nodes containing 11, 6 and 13 are even.
Hence, these nodes have been deleted.
Input: 5 -> 11 -> 16 -> 21 -> 17 -> 10
Output: 5 -> 16 -> 21 -> 10
Explanation:
The linked list contains two digit sum values 11 and 17.
Hence, these nodes have been deleted.
方法：想法是一个遍历循环单链表的节点，对于每个节点，通过迭代每个数字来找到该节点中存在的值的数字总和。如果数字总和为偶数，则删除节点。否则，继续。
下面是上述方法的实现：
C++
// C++ program to remove all
// the Even Digit Sum Nodes from a
// circular singly linked list
#include
using namespace std;
// Structure for a node
struct Node {
int data;
struct Node* next;
};
// Function to insert a node at the beginning
// of a Circular linked list
void push(struct Node** head_ref, int data)
{
// Create a new node and make head as next
// of it.
struct Node* ptr1
= (struct Node*)malloc(
sizeof(struct Node));
struct Node* temp = *head_ref;
ptr1->data = data;
ptr1->next = *head_ref;
// If linked list is not NULL then
// set the next of last node
if (*head_ref != NULL) {
// Find the node before head
// and update next of it.
while (temp->next != *head_ref)
temp = temp->next;
temp->next = ptr1;
}
else
// Point for the first node
ptr1->next = ptr1;
*head_ref = ptr1;
}
// Function to delete the node from a
// Circular Linked list
void deleteNode(Node* head_ref, Node* del)
{
struct Node* temp = head_ref;
// If node to be deleted is head node
if (head_ref == del)
head_ref = del->next;
// Traverse list till not found
// delete node
while (temp->next != del) {
temp = temp->next;
}
// Copy the address of the node
temp->next = del->next;
// Finally, free the memory
// occupied by del
free(del);
return;
}
// Function to find the digit sum
// for a number
int digitSum(int num)
{
int sum = 0;
while (num) {
sum += (num % 10);
num /= 10;
}
return sum;
}
// Function to delete all the Even Digit Sum Nodes
// from the singly circular linked list
void deleteEvenDigitSumNodes(Node* head)
{
struct Node* ptr = head;
struct Node* next;
// Traverse the list till the end
do {
// If the node's data is Fibonacci,
// delete node 'ptr'
if (!(digitSum(ptr->data) & 1))
deleteNode(head, ptr);
// Point to the next node
next = ptr->next;
ptr = next;
} while (ptr != head);
}
// Function to print nodes in a
// given Circular linked list
void printList(struct Node* head)
{
struct Node* temp = head;
if (head != NULL) {
do {
printf("%d ", temp->data);
temp = temp->next;
} while (temp != head);
}
}
// Driver code
int main()
{
// Initialize lists as empty
struct Node* head = NULL;
// Created linked list will be
// 9->11->34->6->13->21
push(&head, 21);
push(&head, 13);
push(&head, 6);
push(&head, 34);
push(&head, 11);
push(&head, 9);
deleteEvenDigitSumNodes(head);
printList(head);
return 0;
} Java
// Java program to remove all
// the Even Digit Sum Nodes from a
// circular singly linked list
import java.util.*;
class GFG{
// Structure for a node
static class Node
{
int data;
Node next;
};
// Function to insert a node at the beginning
// of a Circular linked list
static Node push(Node head_ref, int data)
{
// Create a new node and make head
// as next of it.
Node ptr1 = new Node();
Node temp = head_ref;
ptr1.data = data;
ptr1.next = head_ref;
// If linked list is not null then
// set the next of last node
if (head_ref != null)
{
// Find the node before head
// and update next of it.
while (temp.next != head_ref)
temp = temp.next;
temp.next = ptr1;
}
else
// Point for the first node
ptr1.next = ptr1;
head_ref = ptr1;
return head_ref;
}
// Function to delete the node from a
// Circular Linked list
static void deleteNode(Node head_ref, Node del)
{
Node temp = head_ref;
// If node to be deleted is head node
if (head_ref == del)
head_ref = del.next;
// Traverse list till not found
// delete node
while (temp.next != del)
{
temp = temp.next;
}
// Copy the address of the node
temp.next = del.next;
// Finally, free the memory
// occupied by del
del = null;
return;
}
// Function to find the digit sum
// for a number
static int digitSum(int num)
{
int sum = 0;
while (num > 0)
{
sum += (num % 10);
num /= 10;
}
return sum;
}
// Function to delete all the Even Digit
// Sum Nodes from the singly circular
// linked list
static void deleteEvenDigitSumNodes(Node head)
{
Node ptr = head;
Node next;
// Traverse the list till the end
do
{
// If the node's data is Fibonacci,
// delete node 'ptr'
if (!(digitSum(ptr.data) % 2 == 1))
deleteNode(head, ptr);
// Point to the next node
next = ptr.next;
ptr = next;
} while (ptr != head);
}
// Function to print nodes in a
// given Circular linked list
static void printList(Node head)
{
Node temp = head;
if (head != null)
{
do
{
System.out.printf("%d ", temp.data);
temp = temp.next;
} while (temp != head);
}
}
// Driver code
public static void main(String[] args)
{
// Initialize lists as empty
Node head = null;
// Created linked list will be
// 9.11.34.6.13.21
head = push(head, 21);
head = push(head, 13);
head = push(head, 6);
head = push(head, 34);
head = push(head, 11);
head = push(head, 9);
deleteEvenDigitSumNodes(head);
printList(head);
}
}
// This code is contributed by Amit KatiyarPython3
# Python3 program to remove all
# the Even Digit Sum Nodes from a
# circular singly linked list
# Structure for a node
class Node:
def __init__(self, data):
self.data = data
self.next = None
# Function to insert a node at the beginning
# of a Circular linked list
def push(head_ref, data):
# Create a new node and make head as next
# of it.
ptr1 = Node(data)
temp = head_ref
ptr1.data = data
ptr1.next = head_ref
# If linked list is not None then
# set the next of last node
if (head_ref != None):
# Find the node before head
# and update next of it.
while (temp.next != head_ref):
temp = temp.next
temp.next = ptr1
else:
# Point for the first node
ptr1.next = ptr1
head_ref = ptr1
return head_ref
# Function to deltete the node from a
# Circular Linked list
def delteteNode(head_ref, delt):
temp = head_ref
# If node to be delteted is head node
if (head_ref == delt):
head_ref = delt.next
# Traverse list till not found
# deltete node
while (temp.next != delt):
temp = temp.next
# Copy the address of the node
temp.next = delt.next
# Finally, free the memory
# occupied by delt
del (delt)
return
# Function to find the digit sum
# for a number
def digitSum(num):
sum = 0
while (num != 0):
sum += (num % 10)
num //= 10
return sum
# Function to deltete all the Even Digit
# Sum Nodes from the singly circular linked list
def delteteEvenDigitSumNodes(head):
ptr = head
next = None
# Traverse the list till the end
while True:
# If the node's data is Fibonacci,
# deltete node 'ptr'
if (not (digitSum(ptr.data) & 1)):
delteteNode(head, ptr)
# Point to the next node
next = ptr.next
ptr = next
if (ptr == head):
break
# Function to print nodes in a
# given Circular linked list
def printList(head):
temp = head
if (head != None):
while True:
print(temp.data, end = ' ')
temp = temp.next
if (temp == head):
break
# Driver code
if __name__=='__main__':
# Initialize lists as empty
head = None
# Created linked list will be
# 9.11.34.6.13.21
head = push(head, 21)
head = push(head, 13)
head = push(head, 6)
head = push(head, 34)
head = push(head, 11)
head = push(head, 9)
delteteEvenDigitSumNodes(head)
printList(head)
# This code is contributed by rutvik_56C#
// C# program to remove all
// the Even Digit Sum Nodes from a
// circular singly linked list
using System;
class GFG{
// Structure for a node
class Node
{
public int data;
public Node next;
};
// Function to insert a node
// at the beginning of a
// Circular linked list
static Node push(Node head_ref,
int data)
{
// Create a new node and make head
// as next of it.
Node ptr1 = new Node();
Node temp = head_ref;
ptr1.data = data;
ptr1.next = head_ref;
// If linked list is not null then
// set the next of last node
if (head_ref != null)
{
// Find the node before head
// and update next of it.
while (temp.next != head_ref)
temp = temp.next;
temp.next = ptr1;
}
else
// Point for the first node
ptr1.next = ptr1;
head_ref = ptr1;
return head_ref;
}
// Function to delete the node from a
// Circular Linked list
static void deleteNode(Node head_ref,
Node del)
{
Node temp = head_ref;
// If node to be deleted is head node
if (head_ref == del)
head_ref = del.next;
// Traverse list till not found
// delete node
while (temp.next != del)
{
temp = temp.next;
}
// Copy the address of the node
temp.next = del.next;
// Finally, free the memory
// occupied by del
del = null;
return;
}
// Function to find the digit sum
// for a number
static int digitSum(int num)
{
int sum = 0;
while (num > 0)
{
sum += (num % 10);
num /= 10;
}
return sum;
}
// Function to delete all the Even Digit
// Sum Nodes from the singly circular
// linked list
static void deleteEvenDigitSumNodes(Node head)
{
Node ptr = head;
Node next;
// Traverse the list till the end
do
{
// If the node's data is Fibonacci,
// delete node 'ptr'
if (!(digitSum(ptr.data) % 2 == 1))
deleteNode(head, ptr);
// Point to the next node
next = ptr.next;
ptr = next;
} while (ptr != head);
}
// Function to print nodes in a
// given Circular linked list
static void printList(Node head)
{
Node temp = head;
if (head != null)
{
do
{
Console.Write("{0} ",
temp.data);
temp = temp.next;
} while (temp != head);
}
}
// Driver code
public static void Main(String[] args)
{
// Initialize lists as empty
Node head = null;
// Created linked list will be
// 9.11.34.6.13.21
head = push(head, 21);
head = push(head, 13);
head = push(head, 6);
head = push(head, 34);
head = push(head, 11);
head = push(head, 9);
deleteEvenDigitSumNodes(head);
printList(head);
}
}
// This code is contributed by 29AjayKumar输出：
9 34 21时间复杂度： O(KN) ，其中N是链表的大小，K是链表的最大数目中的位数。