C Exercises: Delete all elements greater than x from a linked list

C Singly Linked List : Exercise-37 with Solution

Write a C program to remove all elements from a singly linked list that are greater than a given value x.

Sample Solution:

C Code:

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

// Structure defining a node in a singly linked list
struct Node {
    int data;           // Data stored in the node
    struct Node* next;  // Pointer to the next node
};

// Function to create a new node with given data
struct Node* newNode(int data) {
    struct Node* node = (struct Node*) malloc(sizeof(struct Node)); // Allocate memory for a new node
    node->data = data;  // Assign data to the new node
    node->next = NULL;  // Initialize the next pointer as NULL
    return node;  // Return the newly created node
}

// Function to delete all elements greater than x from a linked list
void remove_specific(struct Node** head, int x) {
    struct Node* temp = *head;  // Initialize a temporary pointer to the head of the list
    struct Node* prev = NULL;  // Pointer to store the previous node

    // Removing nodes with data greater than x from the start of the list
    while (temp != NULL && temp->data > x) {
        *head = temp->next;  // Update the head to the next node
        free(temp);  // Free the memory of the removed node
        temp = *head;  // Move temp to the new head
    }

    // Traverse the remaining list to remove nodes with data greater than x
    while (temp != NULL) {
        // Traverse until finding a node with data less than or equal to x
        while (temp != NULL && temp->data <= x) {
            prev = temp;  // Store the current node as previous
            temp = temp->next;  // Move to the next node
        }

        // If all remaining nodes are less than or equal to x, exit
        if (temp == NULL) {
            return;
        }

        // Link the previous node to the next node of temp and free temp node
        prev->next = temp->next;
        free(temp);
        temp = prev->next;
    }
}

// Function to print elements of a linked list
void displayList(struct Node* head) {
    while (head) {
        printf("%d ", head->data);  // Print the data of the current node
        head = head->next;  // Move to the next node
    }
    printf("\n");
}

// Main function to demonstrate removing elements greater than x from a linked list
int main() {
    struct Node* head = newNode(1);  // Create the linked list with some initial nodes
    head->next = newNode(2);
    head->next->next = newNode(3);
    head->next->next->next = newNode(4);
    head->next->next->next->next = newNode(5);
    head->next->next->next->next->next = newNode(6);
    head->next->next->next->next->next ->next = newNode(7);
    printf("Original singly linked list:\n");
    displayList(head);  // Display the original list
    printf("\nRemove all elements from the said linked list that are greater than 5:\n");
    remove_specific(&head, 5);  // Remove elements greater than 5 from the list
    displayList(head);  // Display the modified list after removal
    return 0;
}

Sample Output:

Original singly linked list:
1 2 3 4 5 6 7 

Remove all elements from the said linked list that are greater than 5:
1 2 3 4 5 

Flowchart :

C Programming Code Editor:

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