Hash Table Concept and Hash Functions in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a hash table array of size 10.

DSA C

int hashTable[[1]];

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A10

B5

C0

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero size array which is invalid.

Choosing a size too small like 0 or 1.

The hash table size is commonly set to 10 here for simplicity.

2fill in blank

medium

Complete the hash function to compute index using modulo operator.

DSA C

int hashFunction(int key) {
    return key [1] 10;
}

Drag options to blanks, or click blank then click option'

A*

B%

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or multiplication instead of modulo.

Returning key directly without limiting index range.

Modulo operator (%) returns remainder, used to keep index within table size.

3fill in blank

hard

Fix the error in the insertion function to store value at correct index.

DSA C

void insert(int key, int value) {
    int index = hashFunction(key);
    hashTable[[1]] = value;
}

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Akey

Bvalue

ChashTable

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using key as index which may be out of bounds.

Using value or hashTable as index which is incorrect.

We must use the computed index to store the value in the hash table.

4fill in blank

hard

Fill both blanks to complete the search function returning value or -1 if not found.

DSA C

int search(int key) {
    int index = hashFunction(key);
    if (hashTable[[1]] != [2]) {
        return hashTable[index];
    }
    return -1;
}

Drag options to blanks, or click blank then click option'

Aindex

Bkey

C0

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Comparing with key instead of empty value.

Using wrong index or wrong empty value.

Check if the slot at 'index' is not empty (0 means empty here).

5fill in blank

hard

Fill all three blanks to complete a hash function using multiplication and modulo.

DSA C

int hashFunction(int key) {
    int hash = (key [1] 31) [2] 10;
    return hash [3] 0 ? hash : -hash;
}

Drag options to blanks, or click blank then click option'

A*

B%

C>

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of multiplication.

Using wrong comparison operator.

Not handling negative hash values.

Multiply key by 31, modulo 10, then check if hash is positive.