Hash Map vs Array vs Linked List for Lookup in DSA C - Interactive Comparison Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an array of integers with size 5.

DSA C

int arr[[1]];

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A5

B10

C0

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 as size which creates an empty array.

Using size 1 or 10 which does not match the requirement.

The array size must be 5 to hold 5 integers.

2fill in blank

medium

Complete the code to access the third element of the array.

DSA C

int value = arr[[1]];

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A3

B0

C1

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 3 which is the fourth element.

Using index 1 which is the second element.

Array indexing starts at 0, so the third element is at index 2.

3fill in blank

hard

Fix the error in the linked list node definition by completing the pointer declaration.

DSA C

struct Node {
    int data;
    struct Node[1] next;
};

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A*

B&

C[]

D.

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&' which is address-of operator, not pointer declaration.

Using '.' which accesses members, not declares pointers.

The next pointer must be declared as a pointer to struct Node using '*'.

4fill in blank

hard

Fill both blanks to complete the hash map lookup function header and return type.

DSA C

[1] [2](HashMap* map, int key);

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Aint

Blookup

Cvoid

Dinsert

Attempts:

3 left

💡 Hint

Common Mistakes

Using void as return type which means no value returned.

Using insert as function name which is for adding, not lookup.

The function returns an int and is named lookup to find a value by key.

5fill in blank

hard

Fill all three blanks to complete the array search function that returns index or -1 if not found.

DSA C

int search(int arr[], int size, int target) {
    for (int [1] = 0; [2] < size; [3]++) {
        if (arr[i] == target) {
            return i;
        }
    }
    return -1;
}

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Ai

Dj

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causing compilation errors.

Using 'j' which is not declared in the loop.

The loop variable is 'i' used consistently for initialization, condition, and increment.