Occurance of an integer in linked lists

1. Itterative

Algorithm

1. Initialize count as zero.
2. Loop through each element of linked list:
   • If element data is equal to the passed number then increment the count.
3. Return count.

Code

int count(struct Node *head, int search_for)
{
    struct Node *temp = head;
    int cnt = 0;

    while (temp != NULL)
    {
        if (temp->data == search_for)
            cnt++;
        temp = temp->next;
    }
    return cnt;
}

2. Recursive

Algorithm

count(head, key);
if head is NULL
return frequency
if(head->data==key)
increase frequency by 1
count(head->next, key)

Code

int countRec(struct Node *head, int search_for)
{
    if (head == NULL)
        return 0;
    if (head->data == search_for)
        return 1 + countRec(head->next, search_for);
    return countRec(head->next, search_for);
}

Time Complexity: O(N)

References

• GFG: Occurance of an integer in linked lists