---
tags: CS50
---
# (2022年) CS50 week6
其實之前就已經修完 CS50 了，不過因應 2022 年將課堂作業的系統
從 c9.io 換到 github codespace + vscode 整合
打算來重溫一下裡面的作業，並暖身一下 C 語言的手感
由於已經有許多前輩分享課程與作業的心得
加上官網教材的投影片、重點筆記、教學影片都非常完整
故不再做詳細的紀錄，專注在作業 (Lab, Problem sets) 上面
https://cs50.harvard.edu/x/2022/weeks/6/
---
### Lab6： [World Cup](https://cs50.harvard.edu/x/2022/labs/6/)
:::spoiler (點擊展開) 符合 `style50` 風格的程式碼
```python
# Simulate a sports tournament
import csv
import sys
import random
# Number of simluations to run
N = 1000
def main():
# Ensure correct usage
if len(sys.argv) != 2:
sys.exit("Usage: python tournament.py FILENAME")
teams = []
filename = sys.argv[1]
with open(filename) as file:
reader = csv.DictReader(file)
for row in reader:
row["rating"] = int(row["rating"])
teams.append(row)
counts = {}
for i in range(N):
winner = simulate_tournament(teams)
if winner in counts:
counts[winner] += 1
else:
counts[winner] = 1
# Print each team's chances of winning, according to simulation
for team in sorted(counts, key=lambda team: counts[team], reverse=True):
print(f"{team}: {counts[team] * 100 / N:.1f}% chance of winning")
def simulate_game(team1, team2):
"""Simulate a game. Return True if team1 wins, False otherwise."""
rating1 = team1["rating"]
rating2 = team2["rating"]
probability = 1 / (1 + 10 ** ((rating2 - rating1) / 600))
return random.random() < probability
def simulate_round(teams):
"""Simulate a round. Return a list of winning teams."""
winners = []
# Simulate games for all pairs of teams
for i in range(0, len(teams), 2):
if simulate_game(teams[i], teams[i + 1]):
winners.append(teams[i])
else:
winners.append(teams[i + 1])
return winners
def simulate_tournament(teams):
"""Simulate a tournament. Return name of winning team."""
while len(teams) > 1:
teams = simulate_round(teams)
return teams[0]["team"]
if __name__ == "__main__":
main()
```
:::
執行
驗證
---
### 作業： [Hello](https://cs50.harvard.edu/x/2022/psets/6/hello/)
```python
from cs50 import get_string
# get prompt from name
name = get_string("What is your name? \n")
print(f"hello, {name}")
```
執行
驗證
---
### 作業： [Mario-less](https://cs50.harvard.edu/x/2022/psets/6/mario/less/)
:::spoiler (點擊展開) 符合 `style50` 風格的程式碼
```python
from cs50 import get_int
height = get_int("Height: ")
# height must be 1 ~ 8
while (height <= 0 or height > 8):
height = get_int("Enter height from 1 to 8: ")
# head lopp: print each line (assembled content and \n in end)
for i in range(height):
# loop for left space
for j in range(height - i - 1):
print(" ", end="")
# loop for left brick
for k in range(i + 1):
print("#", end="")
print("")
```
:::
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驗證
---
### 作業： [Mario-more](https://cs50.harvard.edu/x/2022/psets/6/mario/more/)
:::spoiler (點擊展開) 符合 `style50` 風格的程式碼
```python
from cs50 import get_int
height = get_int("Height: ")
# height must be 1 ~ 8
while (height <= 0 or height > 8):
height = get_int("Enter height from 1 to 8: ")
# head lopp: print each line (assembled content and \n in end)
for i in range(height):
# loop for left space
for j in range(height - i - 1):
print(" ", end="")
# loop for left brick
for k in range(i + 1):
print("#", end="")
print(" ", end="")
# loop for right brick
for k in range(i + 1):
print("#", end="")
print("")
```
:::
執行
驗證
---
### 作業： [Cash](https://cs50.harvard.edu/x/2022/psets/6/cash/)
:::spoiler (點擊展開) 符合 `style50` 風格的程式碼
```python
import cs50
cash = cs50.get_float("Change owed: ")
if cash > 0:
coin = round(cash*100)
coins = 0
q = 0
d = 0
n = 0
p = 0
# Get quarters values (25¢)
q = int(coin/25)
# Calulate dime value (10¢)
d = int((coin % 25) / 10)
# Calulate nickels value (5¢)
n = int(((coin % 25) % 10) / 5)
# Calulate pennies value (1¢)
p = int(((coin % 25) % 10) % 5)
coins += q + d + n + p
print(coins)
```
:::
執行
驗證
---
### 作業： [Credit](https://cs50.harvard.edu/x/2022/psets/6/credit/)
:::spoiler (點擊展開) 符合 `style50` 風格的程式碼
```python
from cs50 import get_string
# validate card number
def validateCardNumber(card_num):
total = 0
for index, n in enumerate(card_num):
digit = int(n)
# if index is even
if (index % 2 == 0):
total += digit
else:
digit_num = digit * 2
if (digit_num < 9):
total += digit_num
else:
x, y = str(digit_num)
total += int(x)
total += int(y)
return total % 10 == 0
card_number = get_string("Card Number: ")
valid_card_number = validateCardNumber(card_number)
if (valid_card_number == False):
print("INVALID")
pass
# classification card type
# American Express: 15 digit, start with 34, 37
# MasterCard: 16 digit, start with 51, 52, 53, 54, 55
# Visa: 13 or 16 digit, start with 4
first_two = card_number[0:2]
if len(card_number) == 16:
if (first_two[0] == '4'):
print("VISA")
elif ((int(first_two) >= 51) and (int(first_two) <= 55)):
print("MASTERCARD")
else:
print("INVALID")
elif len(card_number) == 15:
is_AMEX = (first_two == '34' or first_two == '37')
print("AMEX") if is_AMEX else print("INVALID")
elif len(card_number) == 13:
is_VISA = (first_two[0] == '4')
print("VISA") if is_VISA else print("INVALID")
else:
print("INVALID")
```
:::
執行
驗證
---
### 作業： [Readability](https://cs50.harvard.edu/x/2022/psets/6/readability/)
:::spoiler (點擊展開) 符合 `style50` 風格的程式碼
```python
from cs50 import get_string
text = get_string("Text: ")
letter_count = 0
word_count = 1 if (len(text) > 0) else 0
sentence_count = 0
for i in range(len(text)):
c = text[i].upper()
# count letters (in ASCII, A ~ Z is 65 ~ 90)
if (ord(c) >= 65 and ord(c) <= 90):
letter_count += 1
# count sentences (in '!', '.', '?)
if (c == '!' or c == '.' or c == '?'):
sentence_count += 1
# count words (in ' ')
if (c == ' '):
word_count += 1
# formula: Coleman-Liau index
# index = 0.0588 * L - 0.296 * S - 15.8
# L is the average number of letters per 100 words in the text
# S is the average number of sentences per 100 words in the text
L = letter_count / float(word_count) * 100
S = sentence_count / float(word_count) * 100
CL_index = 0.0588 * L - 0.296 * S - 15.8
if (CL_index < 1):
print("Before Grade 1")
elif (CL_index >= 16):
print("Grade 16+")
else:
print(f"Grade {round(CL_index)}")
```
:::
執行
驗證
---
### 作業： [DNA](https://cs50.harvard.edu/x/2022/psets/6/dna/)
:::spoiler (點擊展開) 符合 `style50` 風格的程式碼
```python
from sys import argv, exit
import csv
def main():
# Check for command-line usage
if len(argv) != 3:
print("Usage: python dna.py data.csv sequence.txt")
exit(1)
str_keys = []
profiles = []
# Read database file into a variable
# read database file
# using `with` means need not close the file
with open(argv[1], mode="r") as database:
reader = csv.DictReader(database)
str_keys = reader.fieldnames[1:]
# e.g. str_keys => ['AGATC', 'AATG', 'TATC']
for row in reader:
profiles.append(row)
# build dict of STRs size
# e.g. str_dict => [{'AGATC': 0}, {'AATG': 0}, {'TATC': 0}]
str_dict = dict.fromkeys(str_keys, 0)
# Read DNA sequence file into a variable
with open(argv[2], mode="r") as sequence_file:
sequence = sequence_file.readline()
for STR in str_keys:
# find and count str max repeats, and record to dict
str_dict[STR] = find_repeats(sequence, STR)
# print(str_keys)
# print(profiles)
# print(str_dict)
# find match person
for profile in profiles:
match_count = 0
for STR in str_keys:
# compare repeat times in each STR column
if int(profile[STR]) != str_dict[STR]:
continue
match_count += 1
if match_count == len(str_keys):
print(profile['name'])
exit(0)
print("No match")
exit(1)
def longest_match(sequence, subsequence):
"""Returns length of longest run of subsequence in sequence."""
# Initialize variables
longest_run = 0
subsequence_length = len(subsequence)
sequence_length = len(sequence)
# Check each character in sequence for most consecutive runs of subsequence
for i in range(sequence_length):
# Initialize count of consecutive runs
count = 0
# Check for a subsequence match in a "substring" (a subset of characters) within sequence
# If a match, move substring to next potential match in sequence
# Continue moving substring and checking for matches until out of consecutive matches
while True:
# Adjust substring start and end
start = i + count * subsequence_length
end = start + subsequence_length
# If there is a match in the substring
if sequence[start:end] == subsequence:
count += 1
# If there is no match in the substring
else:
break
# Update most consecutive matches found
longest_run = max(longest_run, count)
# After checking for runs at each character in seqeuence, return longest run found
return longest_run
def find_repeats(sequence, STR):
str_len = len(STR)
max_repeats = 0
for i in range(len(sequence)):
repeats = 0
# compare match STR
str_slice = i + str_len
if (sequence[i:str_slice] == STR):
repeats += 1
# continue compare and add to repeats
while sequence[i:str_slice] == sequence[str_slice:str_slice + str_len]:
repeats += 1
i += str_len
str_slice += str_len
# update max repeats
if repeats > max_repeats:
max_repeats = repeats
return max_repeats
if __name__ == "__main__":
main()
```
:::
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