Constructing an optimal Huffman code and tree.

Suppose characters a, b, c, d, e, f, g, h, i, j, k have probabilities 0.01, 0.03, 0.03, 0.05, 0.05, 0.07, 0.09, 0.12, 0.13, 0.20, 0.22, respectively. Construct an optimal Huffman code and draw the Huffman tree.

Use the following rules:
a. Left: 0, right: 1
b. For identical probabilities, group them from the left to right.

What is the average code length?