C++ code for huffman coding using STL

Huffman_coding.cpp

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+// C++ program for Huffman Coding with STL
+#include <bits/stdc++.h>
+using namespace std;
+
+// A Huffman tree node
+struct Node {
+
+	// One of the input characters
+	char data;
+
+	// Frequency of the character
+	unsigned freq;
+
+	// Left and right child
+	Node *left, *right;
+
+	Node(char data, unsigned freq, Node* l = NULL, Node* r = NULL)
+
+	{
+
+		this->left = l;
+		this->right = r;
+		this->data = data;
+		this->freq = freq;
+	}
+};
+
+// For comparison of
+// two heap nodes (needed in min heap)
+struct compare {
+
+	bool operator()(Node* l, Node* r)
+
+	{
+		return (l->freq > r->freq);
+	}
+};
+
+// Prints huffman codes from
+// the root of Huffman Tree.
+void printCodes(struct Node* root, string str)
+{
+
+	if (!root)
+		return;
+
+	if (root->data != '$')
+		cout << root->data << ": " << str << "\n";
+
+	printCodes(root->left, str + "0");
+	printCodes(root->right, str + "1");
+}
+
+// The main function that builds a Huffman Tree and
+// print codes by traversing the built Huffman Tree
+void printHcodes(char arr[], int freq[], int size)
+{
+
+	// Create a min heap & inserts all characters of data[]
+	priority_queue<Node*, vector<Node*>, compare> h;
+
+	for (int i = 0; i < size; ++i)
+		h.push(new Node(arr[i], freq[i]));
+
+	// Iterate while size of heap doesn't become 1
+	while (h.size() > 1) {
+
+		// Extract the two minimum
+		// freq items from min heap
+		Node *l = h.top();h.pop();
+
+		Node *r = h.top();h.pop();
+
+		// Create a new internal node with
+		// frequency equal to the sum of the
+		// two nodes frequencies. Make the
+		// two extracted node as left and right children
+		// of this new node. Add this node
+		// to the min heap '$' is a special value
+		// for internal nodes, not used
+		Node *top = new Node('$', l->freq + r->freq, l, r);
+
+		h.push(top);
+	}
+
+	// Print Huffman codes using
+	// the Huffman tree built above
+	printCodes(h.top(), "");
+}
+
+// Driver Code
+int main()
+{
+
+	char arr[] = { 'a', 'd', 'e', 'f' };
+	int freq[] = { 30, 40, 80, 60 };
+
+	int size = sizeof(arr) / sizeof(arr[0]);
+
+	printHcodes(arr, freq, size);
+
+	return 0;
+}