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DSA Cprogramming~20 mins

Pop Using Linked List Node in DSA C - Practice Problems & Challenges

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Challenge - 5 Problems
🎖️
Linked List Pop Master
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Test your skills under time pressure!
❓ Predict Output
intermediate
2:00remaining
What is the output after popping the head node from the linked list?
Consider a singly linked list with nodes containing values 10 -> 20 -> 30 -> null. The pop operation removes the head node. What is the state of the list after one pop?
DSA C
typedef struct Node {
    int data;
    struct Node* next;
} Node;

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

Node* pop(Node** head) {
    if (*head == NULL) return NULL;
    Node* temp = *head;
    *head = (*head)->next;
    temp->next = NULL;
    return temp;
}

void printList(Node* head) {
    while (head != NULL) {
        printf("%d -> ", head->data);
        head = head->next;
    }
    printf("null\n");
}

int main() {
    Node* head = malloc(sizeof(Node));
    head->data = 10;
    head->next = malloc(sizeof(Node));
    head->next->data = 20;
    head->next->next = malloc(sizeof(Node));
    head->next->next->data = 30;
    head->next->next->next = NULL;

    Node* popped = pop(&head);
    printList(head);
    free(popped);
    // Free remaining nodes omitted for brevity
    return 0;
}
A30 -> null
B20 -> 30 -> null
C10 -> 20 -> 30 -> null
Dnull
Attempts:
2 left
💡 Hint
Pop removes the first node and moves the head pointer to the next node.
❓ Predict Output
intermediate
2:00remaining
What is the output after popping all nodes one by one?
Given a linked list 5 -> 15 -> 25 -> null, pop nodes until the list is empty. What is printed after each pop?
DSA C
typedef struct Node {
    int data;
    struct Node* next;
} Node;

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

Node* pop(Node** head) {
    if (*head == NULL) return NULL;
    Node* temp = *head;
    *head = (*head)->next;
    temp->next = NULL;
    return temp;
}

void printList(Node* head) {
    while (head != NULL) {
        printf("%d -> ", head->data);
        head = head->next;
    }
    printf("null\n");
}

int main() {
    Node* head = malloc(sizeof(Node));
    head->data = 5;
    head->next = malloc(sizeof(Node));
    head->next->data = 15;
    head->next->next = malloc(sizeof(Node));
    head->next->next->data = 25;
    head->next->next->next = NULL;

    for (int i = 0; i < 3; i++) {
        Node* popped = pop(&head);
        printList(head);
        free(popped);
    }
    return 0;
}
A
15 -&gt; 25 -&gt; null
25 -&gt; null
null
B
5 -&gt; 15 -&gt; 25 -&gt; null
15 -&gt; 25 -&gt; null
25 -&gt; null
C
15 -&gt; 25 -&gt; null
null
null
D
null
null
null
Attempts:
2 left
💡 Hint
Each pop removes the head node and updates the list.
❓ Predict Output
advanced
2:00remaining
What error occurs when popping from an empty linked list?
What happens if you call pop on a linked list where the head pointer is NULL?
DSA C
typedef struct Node {
    int data;
    struct Node* next;
} Node;

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

Node* pop(Node** head) {
    if (*head == NULL) return NULL;
    Node* temp = *head;
    *head = (*head)->next;
    temp->next = NULL;
    return temp;
}

int main() {
    Node* head = NULL;
    Node* popped = pop(&head);
    if (popped == NULL) {
        printf("List is empty, nothing to pop.\n");
    }
    return 0;
}
AMemory leak error
BSegmentation fault
CNull pointer dereference error
DList is empty, nothing to pop.
Attempts:
2 left
💡 Hint
Check if head is NULL before popping.
❓ Predict Output
advanced
2:00remaining
What is the output after popping the last node from the list?
Given a linked list with a single node 42 -> null, what is the list state after popping once?
DSA C
typedef struct Node {
    int data;
    struct Node* next;
} Node;

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

Node* pop(Node** head) {
    if (*head == NULL) return NULL;
    Node* temp = *head;
    *head = (*head)->next;
    temp->next = NULL;
    return temp;
}

void printList(Node* head) {
    while (head != NULL) {
        printf("%d -> ", head->data);
        head = head->next;
    }
    printf("null\n");
}

int main() {
    Node* head = malloc(sizeof(Node));
    head->data = 42;
    head->next = NULL;

    Node* popped = pop(&head);
    printList(head);
    free(popped);
    return 0;
}
ASegmentation fault
B42 -> null
Cnull
D42
Attempts:
2 left
💡 Hint
Popping the only node empties the list.
🧠 Conceptual
expert
2:00remaining
What is the time complexity of popping the head node from a singly linked list?
Consider a singly linked list with n nodes. What is the time complexity of the pop operation that removes the head node?
AO(1) - constant time
BO(log n) - logarithmic time
CO(n) - linear time
DO(n^2) - quadratic time
Attempts:
2 left
💡 Hint
Pop only changes the head pointer and frees one node.