check whether two binary trees are identical

Question:

Given two binary trees, check whether they are identical or not.

Analyze:

we first compare the roots of these two trees, if they are the same, we continue to compare the root of their left and right subtrees.

Code:

boolean sameTree(Node a, Node b) { 
  // 1. both empty -> true 
  if (a == null && b == null) return(true);

  // 2. both non-empty -> compare them 
  else if (a!=null && b!=null) { 
    return (a.data == b.data && 
      sameTree(a.leftChild, b.leftChild) && 
      sameTree(a.rightChild, b.rightChild) 
    ); 
  } 
  // 3. one empty, one not -> false 
  else return false; 
} 

refenrence:  http://cslibrary.stanford.edu/110/BinaryTrees.html