Merge pull request #742 from XMadhur/main

Find length of Loop.cpp

Author: spandey1296

Find length of Loop.cpp

@@ -0,0 +1,107 @@
+#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;
+}
+
+int countNodesinLoop(Node* head);
+
+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);
+        
+        cout<< countNodesinLoop(head) << endl;
+    }
+	return 0;
+}
+// } Driver Code Ends
+
+
+/*
+
+struct Node {
+    int data;
+    struct Node *next;
+    Node(int x) {
+        data = x;
+        next = NULL;
+    }
+};
+
+*/
+
+// Your task is to complete the function this function
+// function should return the size of the loop
+
+int count(struct Node *slow)
+{
+    int count=1;
+    struct Node *temp=slow;
+    while(temp->next!=slow)
+    {
+        count++;
+        temp=temp->next;
+    }
+    return count;
+}
+
+int countNodesinLoop(struct Node *head)
+{
+
+    if(head==NULL || head->next==NULL)
+    {
+        return -1;
+    }
+    Node *slow=head;
+    Node *fast=head;
+    while (fast!=NULL && fast->next!=NULL)
+    {
+        slow=slow->next;
+        fast=fast->next->next;
+        if(slow==fast)
+        {
+            return count(slow);
+        }
+
+    }
+    return 0;
+}