Count the number of occurrences of an element in a linked list without using recursion

In this tutorial, we will learn how to find no of occurrences of an element in a linked list without using recursion using the C program? By Piyas Mukherjee Last updated : August 01, 2023

Input

A singly linked list whose address of the first node is stored in a pointer, say head and key is the data of which we have to count the number of occurrences.

Output

The number of times key occurred in the list, (Count)

Data Structure Used

Singly linked list where each node contains a data element say data and the address of the immediate next node say next, with Head holding the address of the first node.

Pseudo Code

Begin
    temp=Head
    Count = 0
    while(temp != NULL)
        begin
            if(temp->data = key)
                count=count+1
            endif
            temp=temp->link
    End while
End

C program to count the number of occurrences of an element in a linked list without using recursion

#include <stdio.h>
#include <stdlib.h>

//linked list node
typedef struct list {
    int data;
    struct list* next;
} node;

int main()
{
    node *head = NULL, *temp, *temp1;
    int choice, count = 0, key;

    //building the linked list
    do {
        temp = (node*)malloc(sizeof(node));
        if (temp != NULL) {
            printf("\nEnter the element in the list : ");
            scanf("%d", &temp->data);
            temp->next = NULL;
            if (head == NULL) {
                head = temp;
            }
            else {
                temp1 = head;
                while (temp1->next != NULL) {
                    temp1 = temp1->next;
                }
                temp1->next = temp;
            }
        }
        else {
            printf("\nMemory not avilable...node allocation is not possible");
        }
        printf("\nIf you wish to add m ore data on the list enter 1 : ");
        scanf("%d", &choice);
    } while (choice == 1);

    //finding occurence of key
    printf("\nEnter the data to find it's occurrence : ");
    scanf("%d", &key);

    temp = head;
    while (temp != NULL) {
        if (temp->data == key) {
            count = count + 1;
        }
        temp = temp->next;
    }
    printf("\n %d occurred %d times in the list", key, count);

    return 0;
}

Output

Enter the element in the list : 1

If you wish to add m ore data on the list enter 1 : 1

Enter the element in the list : 2

If you wish to add m ore data on the list enter 1 : 1

Enter the element in the list : 3

If you wish to add m ore data on the list enter 1 : 1

Enter the element in the list : 4

If you wish to add m ore data on the list enter 1 : 1

Enter the element in the list : 1

If you wish to add m ore data on the list enter 1 : 0

Enter the data to find it's occurrence : 1

1 occurred 2 times in the list