For an intro comp sci lab I'm trying to build a recursive function that counts the number of occurrences of a given letter in a string without using built in methods or loops. I'm pretty stumped without the use of myStr.count. Can anyone offer a tip? should I try something that checks the identity of myStr[0] and returns 0 if letter != myStr[0]?
def count(letter, myStr, theLen):
#Code for def count
def main():
print ("The count of letter a is: ", count("a", "abacdadaad", 10))
print ("The count of letter b is: ", count("b", "abacdadaad", 10))
print ("The count of letter c is: ", count("c", "abacdadaad", 10))
print ("The count of letter d is: ", count("d", "abacdadaad", 10))
main()
Usually, when writing something recursively, the main problem is to determine what is the condition for return. Obviously, when counting letters in a string, it is the moment when you are testing the last character of the string.
You could try:
def recursive(string, letter):
if len(string) == 1 and string == letter:
return 1;
elif len(string) == 1:
return 0;
if string[0] == letter:
count = 1 + recursive(string[1:], letter)
else:
count = recursive(string[1:], letter)
return count
Related
I'm pretty new in Python and I'm trying to make a simple code which returns evens numbers and the largest number i've introduced by command.
#! python3
lista = []
par = set()
num = int(input("Type a number: "))
while num >= 0:
lista.append(num)
num = int(input("Type a number: "))
print()
print(lista)
#print("%s %d" % ("The largest number you introduced is ",max(lista)))
print("The largest number you introduced is {lista:d}".format(lista = max(lista)))
print()
for i in lista:
if i % 2 == 0:
par.add(str(i))
#print(i,end=" ")
print(sorted(par))
print("Even numbers are",", ".join(par),end=".")
The thing is I want It returns a msg like this: "The even numbers are 2, 4, 8, and 10."
I can't find the way to add an and at the end of my sentence. Can someone help me?
So I tried to make a game where the computer chooses a random 4 digit number out of 10 given numbers. The computer then compares the guess of the user with the random chosen code, and will give feedback accordingly:
G = correct digit that is correctly placed
C = correct digit, but incorrectly placed
F = the digit isn't in the code chosen by the computer
However, the feedback doesn't always output correctly.
Fox example, when I guess 9090, the feedback I get is F C F, while the feedback should consist of 4 letters.... How can I fix this?
#chooses the random pincode that needs to be hacked
import random
pincode = [
'1231', '9997', '8829', '6765', '9114', '5673', '0103', '4370', '8301', '1022'
]
name = None
#Main code for the game
def main():
global code
global guess
#Chooses random pincode
code = random.choice(pincode)
#Sets guessestaken to 0
guessesTaken = 0
while guessesTaken < 10:
#Makes sure every turn, an extra guess is added
guessesTaken = guessesTaken + 1
#Asks for user input
print("This is turn " + str(guessesTaken) + ". Try a code!")
guess = input()
#Easteregg codes
e1 = "1955"
e2 = "1980"
#Checks if only numbers have been inputted
if guess.isdigit() == False:
print("You can only use numbers, remember?")
guessesTaken = guessesTaken - 1
continue
#Checks whether guess is 4 numbers long
if len(guess) != len(code):
print("The code is only 4 numbers long! Try again!")
guessesTaken = guessesTaken - 1
continue
#Checks the code
if guess == code:
#In case the user guesses the code in 1 turn
if (guessesTaken) == 1:
print("Well done, " + name + "! You've hacked the code in " +
str(guessesTaken) + " turn!")
#In cases the user guesses the code in more than 1 turn
else:
print("Well done, " + name + "! You've hacked the code in " +
str(guessesTaken) + " turns!")
return
#Sets empty list for the feedback on the user inputted code
feedback = []
nodouble = []
#Iterates from 0 to 4
for i in range(4):
#Compares the items in the list to eachother
if guess[i] == code[i]:
#A match means the letter G is added to feedback
feedback.append("G")
nodouble.append(guess[i])
#Checks if the guess number is contained in the code
elif guess[i] in code:
#Makes sure the position of the numbers isn't the same
if guess[i] != code[i]:
if guess[i] not in nodouble:
#The letter is added to feedback[] if there's a match
feedback.append("C")
nodouble.append(guess[i])
#If the statements above are false, this is executed
elif guess[i] not in code:
#No match at all means an F is added to feedback[]
feedback.append("F")
nodouble.append(guess[i])
#Easteregg
if guess != code and guess == e1 or guess == e2:
print("Yeah!")
guessesTaken = guessesTaken - 1
else:
print(*feedback, sep=' ')
main()
You can try the game here:
https://repl.it/#optimusrobertus/Hack-The-Pincode
EDIT 2:
Here, you can see an example of what I mean.
Here is what I came up with. Let me know if it works.
from random import randint
class PinCodeGame(object):
def __init__(self):
self._attempt = 10
self._code = ['1231', '9997', '8829', '6765', '9114', '5673', '0103', '4370', '8301',
'1022']
self._easterEggs = ['1955', '1980', '1807', '0609']
def introduction(self):
print("Hi there stranger! What do I call you? ")
player_name = input()
return player_name
def show_game_rules(self):
print("10 turns. 4 numbers. The goal? Hack the pincode.")
print(
"For every number in the pincode you've come up with, I'll tell you whether it is correct AND correctly placed (G), correct but placed incorrectly (C) or just plain wrong (F)."
)
def tutorial_needed(self):
# Asks for tutorial
print("Do you want a tutorial? (yes / no)")
tutorial = input().lower()
# While loop for giving the tutorial
while tutorial != "no" or tutorial != "yes":
# Gives tutorial
if tutorial == "yes":
return True
# Skips tutorial
elif tutorial == "no":
return False
# Checks if the correct input has been given
else:
print("Please answer with either yes or no.")
tutorial = input()
def generate_code(self):
return self._code[randint(0, len(self._code))]
def is_valid_guess(self, guess):
return len(guess) == 4 and guess.isdigit()
def play(self, name):
attempts = 0
code = self.generate_code()
digits = [code.count(str(i)) for i in range(10)]
while attempts < self._attempt:
attempts += 1
print("Attempt #", attempts)
guess = input()
hints = ['F'] * 4
count_digits = [i for i in digits]
if self.is_valid_guess(guess):
if guess == code or guess in self._easterEggs:
print("Well done, " + name + "! You've hacked the code in " +
str(attempts) + " turn!")
return True, code
else:
for i, digit in enumerate(guess):
index = int(digit)
if count_digits[index] > 0 and code[i] == digit:
count_digits[index] -= 1
hints[i] = 'G'
elif count_digits[index] > 0:
count_digits[index] -= 1
hints[i] = 'C'
print(*hints, sep=' ')
else:
print("Invalid input, guess should be 4 digits long.")
attempts -= 1
return False, code
def main():
# initialise game
game = PinCodeGame()
player_name = game.introduction()
print("Hi, " + player_name)
if game.tutorial_needed():
game.show_game_rules()
while True:
result, code = game.play(player_name)
if result:
print(
"Oof. You've beaten me.... Do you want to be play again (and be beaten this time)? (yes / no)")
else:
print("Hahahahaha! You've lost! The correct code was " + code +
". Do you want to try again, and win this time? (yes / no)")
play_again = input().lower()
if play_again == "no":
return
main()
Can anyone tell me why when I input 1, 2, 3, and 4 into this code, my output is 6, 2, 3.00? I thought that every time my while loop evaluated to true it would increment the count by one, but the output is not making sense. It's taking the total of 3 of the numbers, but only 2 for the count? I'm probably just overlooking something so an extra pair of eyes would be awesome.
def calcAverage(total, count):
average = float(total)/float(count)
return format(average, ',.2f')
def inputPositiveInteger():
str_in = input("Please enter a positive integer, anything else to quit: ")
if not str_in.isdigit():
return -1
else:
try:
pos_int = int(str_in)
return pos_int
except:
return -1
def main():
total = 0
count = 0
while inputPositiveInteger() != -1:
total += inputPositiveInteger()
count += 1
else:
if count != 0:
print(total)
print(count)
print(calcAverage(total, count))
main()
The error with your code is that on this piece of code...
while inputPositiveInteger() != -1:
total += inputPositiveInteger()
You first call inputPositiveInteger and throw out the result in your condition. You need to store the result, otherwise one input out of two is ignored and the other is added even if it is -1.
num = inputPositiveInteger()
while num != -1:
total += num
count += 1
num = inputPositiveInteger()
Improvements
Although, note that your code can be significantly improved. See the comments in the following improved version of your code.
def calcAverage(total, count):
# In Python3, / is a float division you do not need a float cast
average = total / count
return format(average, ',.2f')
def inputPositiveInteger():
str_int = input("Please enter a positive integer, anything else to quit: ")
# If str_int.isdigit() returns True you can safely assume the int cast will work
return int(str_int) if str_int.isdigit() else -1
# In Python, we usually rely on this format to run the main script
if __name__ == '__main__':
# Using the second form of iter is a neat way to loop over user inputs
nums = iter(inputPositiveInteger, -1)
sum_ = sum(nums)
print(sum_)
print(len(nums))
print(calcAverage(sum_, len(nums)))
One detail worth reading about in the above code is the second form of iter.
def fizz_buzz(i):
if i % 15 == 0:
return ("FizzBuzz")
elif i % 5 == 0:
return ("Buzz")
elif i % 3 == 0:
return ("Fizz")
else:
return (i)
for i in range(1, 21):
print(fizz_buzz(i))
Where and how would do a new line command here with commas?
Trying to get an output like this: 1,2,Fizz,4,Buzz,Fizz,7,8,Fizz,Buzz,11,Fizz,13,14,FizzBuzz,16,17,Fizz,19, Buzz
but sideways and with commas.
Pass end=',' to print()
def fizz_buzz(i):
if i % 15 == 0:
return ("FizzBuzz")
elif i % 5 == 0:
return ("Buzz")
elif i % 3 == 0:
return ("Fizz")
else:
return (i)
for i in range(1, 21):
print(fizz_buzz(i), end=',')
# prints
1,2,Fizz,4,Buzz,Fizz,7,8,Fizz,Buzz,11,Fizz,13,14,FizzBuzz,16,17,Fizz,19,Buzz,
If you do not want the trailing comma, end the range at 20 and follow with print(fizz_buzz(20))
Consider making a list & joining the elements with a comma. There are some great examples here.
For example:
def fizz_buzz(i):
# your code
my_list = []
for i in range(1,21):
my_list.append( str(fizz_buzz(i)) )
print ",".join(my_list)
There are more elegant ways of doing this -- using generators &c, as in the linked answer --, but this simple code will do what you want. Note that the join() method accepts string only, hence the str() in the list.append(); alternatively you could ensure that your fizz_buzz function returns strings regardless.
I have a problem, when in Hangman game there is a word like happy, it only append 1 'p' in the list...run my code and please tell me what to do?
check my loops.
import random
import time
File=open("Dict.txt",'r')
Data = File.read()
Word = Data.split("\n")
A = random.randint(0,len(Word)-1)
Dict = Word[A]
print(Dict)
Dash = []
print("\n\n\t\t\t","_ "*len(Dict),"\n\n")
i = 0
while i < len(Dict):
letter = str(input("\n\nEnter an alphabet: "))
if letter == "" or letter not in 'abcdefghijklmnopqrstuvwxyz' or len(letter) != 1:
print("\n\n\t\tPlease Enter Some valid thing\n\n")
time.sleep(2)
i = i - 1
if letter in Dict:
Dash.append(letter)
else:
print("This is not in the word")
i = i - 1
for item in Dict:
if item in Dash:
print(item, end = " ")
else:
print("_", end = " ")
i = i + 1
The error is with the "break" on Line 25: once you have filled in one space with the letter "p", the loop breaks and will not fill in the second space with "p".
You need to have a flag variable to remember whether any space has been successfully filled in, like this:
success = False
for c in range(len(Dict)):
if x == Dict[c]:
Dash[c] = x
success = True
if not success:
Lives -= 1
P.S. There's something wrong with the indentation of the code you have posted.