给定一个单链表，我们必须将其转换为循环链表。例如，我们得到了一个有四个节点的单链表，我们想把这个单链表转换成循环链表。
null
将上述单链表转换为循环链表。
方法： 其思想是遍历单链表，并检查该节点是否是最后一个节点。如果该节点是最后一个节点，即指向NULL，则将其指向起始节点，即head节点。下面是这种方法的实现。
C++
// Program for converting singly linked list // into circular linked list. #include <bits/stdc++.h> /* Linked list node */ struct Node { int data; struct Node* next; }; // Function that convert singly linked list // into circular linked list. struct Node* circular( struct Node* head) { // declare a node variable start and // assign head node into start node. struct Node* start = head; // check that while head->next not equal // to NULL then head points to next node. while (head->next != NULL) head = head->next; // if head->next points to NULL then // start assign to the head->next node. head->next = start; return start; } void push( struct Node** head, int data) { // Allocate dynamic memory for newNode. struct Node* newNode = ( struct Node*) malloc ( sizeof ( struct Node)); // Assign the data into newNode. newNode->data = data; // newNode->next assign the address of // head node. newNode->next = (*head); // newNode become the headNode. (*head) = newNode; } // Function that display the elements of // circular linked list. void displayList( struct Node* node) { struct Node* start = node; while (node->next != start) { printf ( "%d " , node->data); node = node->next; } // Display the last node of circular // linked list. printf ( "%d " , node->data); } // Driver program to test the functions int main() { // Start with empty list struct Node* head = NULL; // Using push() function to construct // singly linked list // 17->22->13->14->15 push(&head, 15); push(&head, 14); push(&head, 13); push(&head, 22); push(&head, 17); // Call the circular_list function that // convert singly linked list to circular // linked list. circular(head); printf ( "Display list: " ); displayList(head); return 0; } |
JAVA
// Program for converting // singly linked list into // circular linked list. class GFG { /*Linked list node */ static class Node { int data; Node next; }; // Function that convert // singly linked list into // circular linked list. static Node circular(Node head) { // declare a node variable // start and assign head // node into start node. Node start = head; // check that while head.next // not equal to null then head // points to next node. while (head.next != null ) head = head.next; // if head.next points to null // then start assign to the // head.next node. head.next = start; return start; } static Node push(Node head, int data) { // Allocate dynamic memory // for newNode. Node newNode = new Node(); // Assign the data into newNode. newNode.data = data; // newNode.next assign the // address of head node. newNode.next = (head); // newNode become the headNode. (head) = newNode; return head; } // Function that display the elements // of circular linked list. static void displayList( Node node) { Node start = node; while (node.next != start) { System.out.print( " " + node.data); node = node.next; } // Display the last node of // circular linked list. System.out.print( " " + node.data); } // Driver Code public static void main(String args[]) { // Start with empty list Node head = null ; // Using push() function to // convert singly linked list // 17.22.13.14.15 head = push(head, 15 ); head = push(head, 14 ); head = push(head, 13 ); head = push(head, 22 ); head = push(head, 17 ); // Call the circular_list function // that converst singly linked // list to circular linked list. circular(head); System.out.print( "Display list: " ); displayList(head); } } // This code is contributed // by Arnab Kundu |
Python3
# Python3 program for converting # singly linked list into # circular linked list. import sys # Linked list node class Node: def __init__( self ,data): self .data = data self . next = None def push(head, data): if not head: return Node(data) # Allocate dynamic memory # for newNode. # Assign the data into newNode. newNode = Node(data) # newNode.next assign the # address of head node. newNode. next = head # newNode become the headNode. head = newNode return head # Function that convert # singly linked list into # circular linked list. def circular(head): # declare a node variable # start and assign head # node into start node. start = head # check that while head.next # not equal to null then head # points to next node. while (head. next is not None ): head = head. next # if head.next points to null # then start assign to the # head.next node. head. next = start return start # Function that display the elements # of circular linked list. def displayList(node): start = node while (node. next is not start): print ( "{} " . format (node.data),end = "") node = node. next # Display the last node of # circular linked list. print ( "{} " . format (node.data),end = "") # Driver Code if __name__ = = '__main__' : # Start with empty list head = None # Using push() function to # convert singly linked list # 17.22.13.14.15 head = push(head, 15 ) head = push(head, 14 ) head = push(head, 13 ) head = push(head, 22 ) head = push(head, 17 ) # Call the circular_list function # that converst singly linked # list to circular linked list. circular(head) print ( "Display List:" ) displayList(head) # This Code is Contributed By Vikash Kumar 37 |
C#
// C# Program for converting // singly linked list into // circular linked list. using System; class GFG { /*Linked list node */ public class Node { public int data; public Node next; }; // Function that convert // singly linked list into // circular linked list. static Node circular(Node head) { // declare a node variable // start and assign head // node into start node. Node start = head; // check that while head.next // not equal to null then head // points to next node. while (head.next != null ) head = head.next; // if head.next points to null // then start assign to the // head.next node. head.next = start; return start; } static Node push(Node head, int data) { // Allocate dynamic memory // for newNode. Node newNode = new Node(); // Assign the data into newNode. newNode.data = data; // newNode.next assign the // address of head node. newNode.next = (head); // newNode become the headNode. (head) = newNode; return head; } // Function that display the elements // of circular linked list. static void displayList( Node node) { Node start = node; while (node.next != start) { Console.Write( " " + node.data); node = node.next; } // Display the last node of // circular linked list. Console.Write( " " + node.data); } // Driver Code public static void Main(String []args) { // Start with empty list Node head = null ; // Using push() function to // convert singly linked list // 17.22.13.14.15 head = push(head, 15); head = push(head, 14); head = push(head, 13); head = push(head, 22); head = push(head, 17); // Call the circular_list function // that converst singly linked // list to circular linked list. circular(head); Console.Write( "Display list: " ); displayList(head); } } // This code is contributed 29AjayKumar |
Javascript
<script> // Javascript Program for converting // singly linked list into // circular linked list. /* Linked list node */ class Node { constructor(val) { this .data = val; this .next = null ; } } // Function that convert // singly linked list into // circular linked list. function circular( head) { // declare a node variable // start and assign head // node into start node. start = head; // check that while head.next // not equal to null then head // points to next node. while (head.next != null ) head = head.next; // if head.next points to null // then start assign to the // head.next node. head.next = start; return start; } function push( head , data) { // Allocate dynamic memory // for newNode. newNode = new Node(); // Assign the data into newNode. newNode.data = data; // newNode.next assign the // address of head node. newNode.next = (head); // newNode become the headNode. (head) = newNode; return head; } // Function that display the elements // of circular linked list. function displayList( node) { start = node; while (node.next != start) { document.write( " " + node.data); node = node.next; } // Display the last node of // circular linked list. document.write( " " + node.data); } // Driver Code // Start with empty list head = null ; // Using push() function to // convert singly linked list // 17.22.13.14.15 head = push(head, 15); head = push(head, 14); head = push(head, 13); head = push(head, 22); head = push(head, 17); // Call the circular_list function // that converst singly linked // list to circular linked list. circular(head); document.write( "Display list: <br/>" ); displayList(head); // This code is contributed by gauravrajput1 </script> |
输出：
Display list:17 22 13 14 15
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