210322 TIL

1.English

all I only wanna do is see some public facilities so that I can imagine and understand the way of lives of people who have lived there for long time

 

2.datacamp

after table has PK, we can designate FK to new column of new table with this way. 

1)create first table

2)insert some values to the table

3)create another table

4)bring PK function from the first table to second table’s new column as FK

5)now, they are connected. (only cars with valid and existing manufacturers may be entered into that table

 

3.algorithm

translate from what I think to code

effectiveness - optimization of module and function that I use frequently

think based on procedure - make my own workflow

debugging - find errors in process

 

[Big O notation] - how many times what I code would run? 

 

time complexity (always should consider the worst)

-O(1) once

-O(n) n times

 

def search(lst, N, K)

for i in lst

if i == K: return True

return false

 

-O(logN) best example - binary search (up & down game)

 

keep getting short by half, this means log2N.

We can detach ‘2’, it turns out logN

 

[1, 2, 3, 4], 4, 3

 

def binary_search(lst, N, K):

lo, hi = 0, N-1. # start from zero

while lo <= hi: # during hi bigger than zero

mid = (lo + hi)  // 2 # share

if lst[mid] == K : return True # completed!

if lst[mid] > K : lo = mid - 1

else: lo = mid + 1 # rearrange location of lo

return False

 

## this could work when the list are sorted before ##

 

4.python bootcamp day4 of udemy

rock, paper, scissors

1)question

2)random result from computer

3)compare mine with computers’

4)print result

import random

mine = int(input("which one would you choose? rock is 0, paper is 1, scissors is 2: "))

com = random.randint(0,2)

row1 = ['draw game', 'you are lost', 'you win']
row2 = ['you win', 'draw game', 'you are lost']
row3 = ['you are lost', 'you win', 'draw game']

judgement = [row1, row2, row3]

if mine == 0:
  print(rock)
elif mine == 1:
  print(paper)
else:
  print(scissors)

if com == 0:
  print(rock)
elif com == 1:
  print(paper)
else:
  print(scissors)

print(judgement[mine][com])

# refactoring by teacher

game_image = [rock, paper, scissors]

user_choice = int(input("what do you choose? Type 0 for Rock, 1 for Paper, or 2 for Scissors \n"))
computer_choice = random.randint(0,2)

if user_choice >= 3 or user_choice < 0:
  print("you put the invalied number, you lose")
else:
  print(game_image[user_choice])
  print("computer chose:")
  print(game_image[computer_choice])

  if user_choice == 0 and computer_choice == 2:
    print("you win")
  elif computer_choice == 0 and user_choice == 2:
    print("you lose")
  elif user_choice > computer_choice:
    print("you win")
  elif computer_choice > user_choice:
    print("you lose")

debugging!!