Determine if two binary trees are equal

Question

What would be the efficient algorithm to find if two given binary trees are equal - in structure and content?

Answer 1

Modulo stack overflow, something like

eq(t1, t2) =
    eq(t1.left, t2.left) && t1.data=t2.data && eq(t1.right, t2.right)

(This generalizes to an equality predicate for all tree-structured algebraic data types - for any piece of structured data, check if each of its sub-parts are equal to each of the other one's sub-parts.)