Lecture Note for April 28, 2019 - GeekDojo Mock Contest 1

Review

Last week’s homework:

• Two-Sum - https://leetcode.com/problems/two-sum/

Tips on solving problems

• Read a problem statement twice! (Don’t solve a wrong problem!)
• Measure twice, cut once! (Write a concrete example on a paper, write an algorithm or peusdo-code, and test the algorithm before starting to write code)
• After solving a problem, study Editorial and view solutions in Discussion.
• Upsolve - After competition, solve problems that you couldn’t finish. If you do this, you are already ahead of 99% of others.

Cheatsheet

Iterating 2D list

A = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

# Iterate 2D list
for i in range(len(A)):
  for j in range(len(A[0]):
    print(A[i][j])

Hashtable

from collections import defaultdict

my_dict = defaultdict(int)  # Create a dictionary where value is integer
my_dct['a'] = 1

Homework:

• Upsolve the Mock Contest 1 - www.hackerrank.com/geekdojo-mock-competition-1