Construct a huffman tree using greedy strategy for the following character and their frequency i)Encode: state ii)Decode:010010001 code example
Example: huffman coding algorithm code
// Huffman Coding in C++
using namespace std;
struct MinHNode {
unsigned freq;
char item;
struct MinHNode *left, *right;
};
struct MinH {
unsigned size;
unsigned capacity;
struct MinHNode **array;
};
// Creating Huffman tree node
struct MinHNode *newNode(char item, unsigned freq) {
struct MinHNode *temp = (struct MinHNode *)malloc(sizeof(struct MinHNode));
temp->left = temp->right = NULL;
temp->item = item;
temp->freq = freq;
return temp;
}
// Create min heap using given capacity
struct MinH *createMinH(unsigned capacity) {
struct MinH *minHeap = (struct MinH *)malloc(sizeof(struct MinH));
minHeap->size = 0;
minHeap->capacity = capacity;
minHeap->array = (struct MinHNode **)malloc(minHeap->capacity * sizeof(struct MinHNode *));
return minHeap;
}
// Swap function
void swapMinHNode(struct MinHNode **a, struct MinHNode **b) {
struct MinHNode *t = *a;
*a = *b;
*b = t;
}
// Heapify
void minHeapify(struct MinH *minHeap, int idx) {
int smallest = idx;
int left = 2 * idx + 1;
int right = 2 * idx + 2;
if (left < minHeap->size && minHeap->array[left]->freq < minHeap->array[smallest]->freq)
smallest = left;
if (right < minHeap->size && minHeap->array[right]->freq < minHeap->array[smallest]->freq)
smallest = right;
if (smallest != idx) {
swapMinHNode(&minHeap->array[smallest],
&minHeap->array[idx]);
minHeapify(minHeap, smallest);
}
}
// Check if size if 1
int checkSizeOne(struct MinH *minHeap) {
return (minHeap->size == 1);
}
// Extract the min
struct MinHNode *extractMin(struct MinH *minHeap) {
struct MinHNode *temp = minHeap->array[0];
minHeap->array[0] = minHeap->array[minHeap->size - 1];
--minHeap->size;
minHeapify(minHeap, 0);
return temp;
}
// Insertion
void insertMinHeap(struct MinH *minHeap, struct MinHNode *minHeapNode) {
++minHeap->size;
int i = minHeap->size - 1;
while (i && minHeapNode->freq < minHeap->array[(i - 1) / 2]->freq) {
minHeap->array[i] = minHeap->array[(i - 1) / 2];
i = (i - 1) / 2;
}
minHeap->array[i] = minHeapNode;
}
// BUild min heap
void buildMinHeap(struct MinH *minHeap) {
int n = minHeap->size - 1;
int i;
for (i = (n - 1) / 2; i >= 0; --i)
minHeapify(minHeap, i);
}
int isLeaf(struct MinHNode *root) {
return !(root->left) && !(root->right);
}
struct MinH *createAndBuildMinHeap(char item[], int freq[], int size) {
struct MinH *minHeap = createMinH(size);
for (int i = 0; i < size; ++i)
minHeap->array[i] = newNode(item[i], freq[i]);
minHeap->size = size;
buildMinHeap(minHeap);
return minHeap;
}
struct MinHNode *buildHfTree(char item[], int freq[], int size) {
struct MinHNode *left, *right, *top;
struct MinH *minHeap = createAndBuildMinHeap(item, freq, size);
while (!checkSizeOne(minHeap)) {
left = extractMin(minHeap);
right = extractMin(minHeap);
top = newNode('$', left->freq + right->freq);
top->left = left;
top->right = right;
insertMinHeap(minHeap, top);
}
return extractMin(minHeap);
}
void printHCodes(struct MinHNode *root, int arr[], int top) {
if (root->left) {
arr[top] = 0;
printHCodes(root->left, arr, top + 1);
}
if (root->right) {
arr[top] = 1;
printHCodes(root->right, arr, top + 1);
}
if (isLeaf(root)) {
cout << root->item << " | ";
printArray(arr, top);
}
}
// Wrapper function
void HuffmanCodes(char item[], int freq[], int size) {
struct MinHNode *root = buildHfTree(item, freq, size);
int arr[MAX_TREE_HT], top = 0;
printHCodes(root, arr, top);
}
// Print the array
void printArray(int arr[], int n) {
int i;
for (i = 0; i < n; ++i)
cout << arr[i];
cout << "\n";
}
int main() {
char arr[] = {'A', 'B', 'C', 'D'};
int freq[] = {5, 1, 6, 3};
int size = sizeof(arr) / sizeof(arr[0]);
cout << "Char | Huffman code ";
cout << "\n----------------------\n";
HuffmanCodes(arr, freq, size);
}