#include <stdio.h>
#include <stdlib.h>
#define MAX_TREE_HT 100
struct
MinHeapNode {
char
data;
unsigned freq;
struct
MinHeapNode *left, *right;
};
struct
MinHeap {
unsigned size;
unsigned capacity;
struct
MinHeapNode** array;
};
struct
MinHeapNode* newNode(
char
data, unsigned freq)
{
struct
MinHeapNode* temp = (
struct
MinHeapNode*)
malloc
(
sizeof
(
struct
MinHeapNode));
temp->left = temp->right = NULL;
temp->data = data;
temp->freq = freq;
return
temp;
}
struct
MinHeap* createMinHeap(unsigned capacity)
{
struct
MinHeap* minHeap
= (
struct
MinHeap*)
malloc
(
sizeof
(
struct
MinHeap));
minHeap->size = 0;
minHeap->capacity = capacity;
minHeap->array = (
struct
MinHeapNode**)
malloc
(
minHeap->capacity *
sizeof
(
struct
MinHeapNode*));
return
minHeap;
}
void
swapMinHeapNode(
struct
MinHeapNode** a,
struct
MinHeapNode** b)
{
struct
MinHeapNode* t = *a;
*a = *b;
*b = t;
}
void
minHeapify(
struct
MinHeap* 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) {
swapMinHeapNode(&minHeap->array[smallest],
&minHeap->array[idx]);
minHeapify(minHeap, smallest);
}
}
int
isSizeOne(
struct
MinHeap* minHeap)
{
return
(minHeap->size == 1);
}
struct
MinHeapNode* extractMin(
struct
MinHeap* minHeap)
{
struct
MinHeapNode* temp = minHeap->array[0];
minHeap->array[0] = minHeap->array[minHeap->size - 1];
--minHeap->size;
minHeapify(minHeap, 0);
return
temp;
}
void
insertMinHeap(
struct
MinHeap* minHeap,
struct
MinHeapNode* 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;
}
void
buildMinHeap(
struct
MinHeap* minHeap)
{
int
n = minHeap->size - 1;
int
i;
for
(i = (n - 1) / 2; i >= 0; --i)
minHeapify(minHeap, i);
}
void
printArr(
int
arr[],
int
n)
{
int
i;
for
(i = 0; i < n; ++i)
printf
(
"%d"
, arr[i]);
printf
(
"\n"
);
}
int
isLeaf(
struct
MinHeapNode* root)
{
return
!(root->left) && !(root->right);
}
struct
MinHeap* createAndBuildMinHeap(
char
data[],
int
freq[],
int
size)
{
struct
MinHeap* minHeap = createMinHeap(size);
for
(
int
i = 0; i < size; ++i)
minHeap->array[i] = newNode(data[i], freq[i]);
minHeap->size = size;
buildMinHeap(minHeap);
return
minHeap;
}
struct
MinHeapNode* buildHuffmanTree(
char
data[],
int
freq[],
int
size)
{
struct
MinHeapNode *left, *right, *top;
struct
MinHeap* minHeap
= createAndBuildMinHeap(data, freq, size);
while
(!isSizeOne(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
printCodes(
struct
MinHeapNode* root,
int
arr[],
int
top)
{
if
(root->left) {
arr[top] = 0;
printCodes(root->left, arr, top + 1);
}
if
(root->right) {
arr[top] = 1;
printCodes(root->right, arr, top + 1);
}
if
(isLeaf(root)) {
printf
(
"%c: "
, root->data);
printArr(arr, top);
}
}
void
HuffmanCodes(
char
data[],
int
freq[],
int
size)
{
struct
MinHeapNode* root
= buildHuffmanTree(data, freq, size);
int
arr[MAX_TREE_HT], top = 0;
printCodes(root, arr, top);
}
int
main()
{
char
arr[] = {
'a'
,
'b'
,
'c'
,
'd'
,
'e'
,
'f'
};
int
freq[] = { 5, 9, 12, 13, 16, 45 };
int
size =
sizeof
(arr) /
sizeof
(arr[0]);
HuffmanCodes(arr, freq, size);
return
0;
}