FrequencyOfNumberInLinkedList.cpp

// C++ program to count occurrences in a linked list 
#include <bits/stdc++.h> 
#include <iostream>
using namespace std; 

/* Link list node */
class Node { 
public: 
	int data; 
	Node* next; 
}; 

/* Given a reference (pointer to pointer) to the head 
of a list and an int, push a new node on the front 
of the list. */
void push(Node** head_ref, int new_data) 
{ 
	/* allocate node */
	Node* new_node = new Node(); 

	/* put in the data */
	new_node->data = new_data; 

	/* link the old list off the new node */
	new_node->next = (*head_ref); 

	/* move the head to point to the new node */
	(*head_ref) = new_node; 
} 

/* Counts the no. of occurrences of a node 
(search_for) in a linked list (head)*/
int count(Node* head, int search_for) 
{ 
	Node* current = head; 
	int count = 0; 
	while (current != NULL) { 
		if (current->data == search_for) 
			count++; 
		current = current->next; 
	} 
	return count; 
} 


int main() 
{ 
	/* Start with the empty list */
	Node* head = NULL; 

	
	push(&head, 1); 
	push(&head, 3); 
	push(&head, 1); 
	push(&head, 2); 
	push(&head, 1); 

	
	cout << "count of 1 is " << count(head, 1); 
	return 0; 
}