Is the code A: $11,$ B: $10,$ C: $0$ a prefix code?

Construct an expression tree for $(3+x)-5*y$ and write this expression is prefix form and postfix form.

Use a depth$-$first search to find a spanning tree of the following graph. Start at the vertex $a,$ and use

alphabetical order.

Use Prim's algorithm to find a minimum spanning tree for the following weighted graph. Use alphabetical

order to break ties.