Subtree of Another Tree

LeetCode Q 572 - Subtree of Another Tree

Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node’s descendants. The tree s could also be considered as a subtree of itself.

Solution:

Code:

public boolean isSubtree(TreeNode s, TreeNode t) {
  if (s == null && t == null) return true;
  if (s == null || t == null) return false;
  
  if (s.val == t.val && isSame(s, t))
    return true;
  
  return isSubtree(s.left, t) || isSubtree(s.right, t);
}
    
private boolean isSame(TreeNode s, TreeNode t) {
  if (s == null && t == null) return true;
  if (s == null || t == null || s.val != t.val) return false;
  return isSame(s.left, t.left) && isSame(s.right, t.right);
}