Huffman Encoding in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new node for the Huffman tree.

DSA C

struct Node* createNode(char data, unsigned freq) {
    struct Node* temp = (struct Node*)malloc(sizeof(struct Node));
    temp->data = [1];
    temp->freq = freq;
    temp->left = temp->right = NULL;
    return temp;
}

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

Adata

Bfreq

C'\0'

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning frequency to data field.

Assigning NULL or zero character instead of actual data.

The node's data field should be set to the character passed as 'data'.

2fill in blank

medium

Complete the code to check if a node is a leaf node in the Huffman tree.

DSA C

int isLeaf(struct Node* root) {
    return (root->left == NULL && root->right [1] NULL);
}

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

A<

B>

C!=

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '!=' instead of '==' causing wrong leaf detection.

Using relational operators like '>' or '<' which are invalid for pointers.

A leaf node has both left and right pointers equal to NULL.

3fill in blank

hard

Fix the error in the code that inserts a node into the min heap.

DSA C

void insertMinHeap(struct MinHeap* minHeap, struct Node* node) {
    ++minHeap->size;
    int i = minHeap->size - 1;
    while (i && node->freq < minHeap->array[(i - 1) / 2]->freq) {
        minHeap->array[i] = minHeap->array[(i - 1) / 2];
        i = [1];
    }
    minHeap->array[i] = node;
}

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

Ai / 2

B(i - 1) / 2

Ci - 1

Di + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using i - 1 moves one step left, not to parent.

Using i / 2 is incorrect for zero-based indexing.

Using i + 1 moves down, not up.

To move up the heap, update i to the parent's index: (i - 1) / 2.

4fill in blank

hard

Fill both blanks to build the Huffman tree by extracting two minimum nodes and combining them.

DSA C

while (minHeap->size != 1) {
    struct Node* left = extractMin(minHeap);
    struct Node* right = extractMin(minHeap);
    struct Node* top = createNode('[1]', left->freq + right->freq);
    top->left = left;
    top->right = right;
    insertMinHeap(minHeap, top);
}

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

A'\0'

B'*'

C'$'

D' '

Attempts:

3 left

💡 Hint

Common Mistakes

Using actual characters from input instead of a special marker.

Using null character '\0' which may cause confusion.

The internal nodes use a special character like '$' to indicate they are not leaves.

5fill in blank

hard

Fill the blanks to print the Huffman codes by traversing the tree recursively.

DSA C

void printCodes(struct Node* root, int arr[], int top) {
    if (root->left) {
        arr[top] = [1];
        printCodes(root->left, arr, top + 1);
    }
    if (root->right) {
        arr[top] = [2];
        printCodes(root->right, arr, top + 1);
    }
    if (isLeaf(root)) {
        printf("%c: ", root->data);
        for (int i = 0; i < top; ++i) {
            printf("%d", arr[i]);
        }
        printf("\n");
    }
}

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

A0

B1

C2

D-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 2 or -1 which are invalid for binary codes.

Swapping 0 and 1 causing incorrect codes.

Left edges are marked with 0, right edges with 1. The option '2' is a distractor and not used here.