see the pic for the complete question format $,$Let $TRE{E}_{n,k}$ be the class of all functions computed by a decision tree on $n$ and with $k$ leaves.

Show that $TRE{E}_{n,n}$ is efficiently reducible to $DN{F}_{n,n}$

${?}^1$ I.e$.,$ a binary tree in which every node has exactly two or zero children.