4. We use Huffman’s algorithm to obtain an encoding of alphabet fa, b, c, d with frequencies fa, fb, fe, fa. Assume that f fi f2fd List all possible different coding trees that could be obtained (consider two trees to be the same if one tree can be obtained from the other one by changing the order of children of nodes and/or exchanging 0/1 labels on edges connecting nodes to their children).
OR
OR