Detect a Loop in a Linked List in python , java and c

Using Python

class ListNode:
    def __init__(self, val):
        self.val = val
        self.next = None

def has_cycle(head):
    slow = head
    fast = head

    while fast is not None and fast.next is not None:
        slow = slow.next
        fast = fast.next.next

        if slow == fast:
            return True

    return False

# Creating a linked list with a loop
head = ListNode(1)
head.next = ListNode(2)
head.next.next = ListNode(3)
head.next.next.next = ListNode(4)
head.next.next.next.next = ListNode(5)
head.next.next.next.next.next = head.next  # Creating a loop

print("Has cycle:", has_cycle(head))

Using Java

class ListNode {
    int val;
    ListNode next;

    ListNode(int val) {
        this.val = val;
        this.next = null;
    }
}

public class LinkedListCycle {
    public boolean hasCycle(ListNode head) {
        if (head == null || head.next == null) {
            return false;
        }

        ListNode slow = head;
        ListNode fast = head;

        while (fast != null && fast.next != null) {
            slow = slow.next;
            fast = fast.next.next;

            if (slow == fast) {
                return true;
            }
        }

        return false;
    }

    public static void main(String[] args) {
        ListNode head = new ListNode(1);
        head.next = new ListNode(2);
        head.next.next = new ListNode(3);
        head.next.next.next = new ListNode(4);
        head.next.next.next.next = new ListNode(5);
        head.next.next.next.next.next = head.next; // Creating a loop

        LinkedListCycle cycleDetector = new LinkedListCycle();
        System.out.println("Has cycle: " + cycleDetector.hasCycle(head));
    }
}

Using C

#include <stdio.h>
#include <stdbool.h>

struct ListNode {
    int val;
    struct ListNode* next;
};

bool hasCycle(struct ListNode* head) {
    if (head == NULL || head->next == NULL) {
        return false;
    }

    struct ListNode* slow = head;
    struct ListNode* fast = head;

    while (fast != NULL && fast->next != NULL) {
        slow = slow->next;
        fast = fast->next->next;

        if (slow == fast) {
            return true;
        }
    }

    return false;
}

int main() {
    struct ListNode* head = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->val = 1;
    head->next = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->next->val = 2;
    head->next->next = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->next->next->val = 3;
    head->next->next->next = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->next->next->next->val = 4;
    head->next->next->next->next = (struct ListNode*)malloc(sizeof(struct ListNode));
    head->next->next->next->next->val = 5;
    head->next->next->next->next->next = head->next; // Creating a loop

    printf("Has cycle: %s\n", hasCycle(head) ? "true" : "false");

    return 0;
}