Brain Dump

Algorithms

Mistakes

Updated at: 23 Apr 2019 08:03:44

This file is to keep track of all mistakes made in my code/problem solving.

Strings

Remember that some strings have spaces in them. Upper case, lower case.

Trees

def inorder(self, root): if root is not None: for val in self.inorder(root.left): yield val yield root.val for val in self.inorder(root.right): yield val

It is often a good idea to use a generator as a generator will yield a more elegant solution. We can use iteration instead of recursion. (Problem: Range sum of BST)

Graph

Think first about the right representation. If dfs traversal is needed, NEVER use matrix representation unless its searching 1 row/col away

In matrix dfs, REMEMBER to check bounds

LinkedList

Reversing singly linked list

  1. Use the parameter to store the previous value, and assign
  2. Use it recursively.

When implementing skipping, must use the .next instead of the node itself.

General

  1. Off by 1
  2. If there is a valid/invalid state, ask what happens if starting value is valid, invalid
  3. Boolean optimization: if not reg and not string: return True if not reg return False if not reg: return not String