https://www.rik-kisnah.ai/tags/trees/Recent content in Trees on Rik Kisnah - BlogHugoenTue, 17 Sep 2019 09:00:00 -0700https://www.rik-kisnah.ai/teach/coding/validate-a-binary-search-tree/Tue, 17 Sep 2019 09:00:00 -0700https://www.rik-kisnah.ai/teach/coding/validate-a-binary-search-tree/Is every node bigger than everything on its left and smaller than everything on its right? Checking only the children is the famous wrong answer. Carry a range down the tree instead.https://www.rik-kisnah.ai/teach/coding/invert-a-binary-tree/Tue, 09 Oct 2018 09:00:00 -0700https://www.rik-kisnah.ai/teach/coding/invert-a-binary-tree/Swap left and right at every node. Three lines of recursion. The problem is a meme, but it is the cleanest test I know of whether you can trust a recursive call to do its job.