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Do division or power calculation without language provided operators – we see this sort of questions among algorithm problems. I wrote Addtion without +/- operators in the post about XOR related questions. “Divide without division” and “power without its operator or function” are examples as well.

Serialize, Deserialize a binary tree are a popular algorithm questions It depends on a programming language, but in most cases, a binary tree is expressed by an object tree. Each node can have at most two children: left node and right node. Once the binary tree is constructed, it is not language neutral anymore.

As a lisp family language programmer, I used to write a lot of parentheses. Specifically, ( and ). In an algorithm world, parentheses often includes other brackets as well, such as {} or [], but that’s it. At most three types of pairs are there, some problems are much complicated to find a solution. This post is about such problems.

“Count how may ways to do …” is one type of algorithm questions. For example, count ways to climb up stairs, count ways to make sum by given coins, or count ways to reach from top left to bottom right corner.

We often see problems related to a palindrome or palindromic something. Palindrome is, like “racecar,” a reversed and original are exactly the same string. We see really many types of palindrome related problems. Sometime, problems are based on palindromic substrings. Sometime, those are palindromic subsequences.