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Detect Loop in linked list.cpp
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Detect Loop in linked list.cpp
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//{ Driver Code Starts
// Initial template code for C++
#include <bits/stdc++.h>
using namespace std;
struct Node
{
int data;
Node *next;
Node(int val)
{
data = val;
next = NULL;
}
};
void loopHere(Node *head, Node *tail, int position)
{
if (position == 0)
return;
Node *walk = head;
for (int i = 1; i < position; i++)
walk = walk->next;
tail->next = walk;
}
// } Driver Code Ends
// User function template for C++
/*
struct Node
{
int data;
struct Node *next;
Node(int x) {
data = x;
next = NULL;
}
*/
class Solution
{
public:
// Function to check if the linked list has a loop.
bool detectLoop(Node *head)
{
Node *slow = head;
Node *fast = head;
while (fast != NULL && fast->next != NULL)
{
slow = slow->next;
fast = fast->next->next;
if (slow == fast)
{
return true;
}
}
return false;
}
};
//{ Driver Code Starts.
int main()
{
int t;
cin >> t;
while (t--)
{
int n, num;
cin >> n;
Node *head, *tail;
cin >> num;
head = tail = new Node(num);
for (int i = 0; i < n - 1; i++)
{
cin >> num;
tail->next = new Node(num);
tail = tail->next;
}
int pos;
cin >> pos;
loopHere(head, tail, pos);
Solution ob;
if (ob.detectLoop(head))
cout << "True\n";
else
cout << "False\n";
}
return 0;
}
// } Driver Code Ends