First Thoughts: cannot return two boolean returns, and since we are only interested in whether there is at least one fault (different value or different structure -> when first tree has a value and the second tree has no value in the same corresponding position) we can use the && value of the return boolean. If at least one is false, the answer should give false. If both trees are null, should return true.
My Solution:
public boolean isSameTree(TreeNode p, TreeNode q) {
if (p==null&&q!=null) return false;
if (p!=null&&q==null) return false;
if (p==null&&q==null) return true;
if (p.val!=q.val) return false;
return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}Catch Point:
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one way to encompass the two boolean return results could be to use the && operator on the two return values.
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repositioning of the conditional statements above could shorten solution (if we first check both are null), but not a big problem.
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think about the smaller problem. if confused whether both null case should return true or false, just think of the case where we are simply given two null trees.
