// Algorithm: Huffman Coding
// Type: Greedy
// Time Complexity: O(n log n)       // where n is number of characters
// Space Complexity: O(n)            // for priority queue and tree

function HuffmanCoding(charFreq):
    create priorityQueue Q and insert all characters with freq

    while Q has more than 1 node:
        left = Q.popMin()
        right = Q.popMin()
        newNode = merge(left, right)
        Q.insert(newNode)

    return Q.pop()  // root of Huffman Tree

function printCodes(root, code):
    if root is a leaf:
        print root.char and code
    else:
        printCodes(root.left, code + "0")
        printCodes(root.right, code + "1")