PROBLEM SET 1: MATH INTERPRETER | SOLUTION (CS50 PYTHON)

––– DISCLAIMER –––

The following videos are for educational purposes only. Cheating or any other activities are highly discouraged!! Using another person’s code breaks the academic honesty guidelines. This solution is for those who have finished the problem sets and want to watch for educational purposes, learning experience, and exploring alternative ways to approach problems and is NOT meant for those actively doing the problem sets. All problem sets presented in this video are owned by Harvard University.

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[moeletsimelamu]

This problem is actually easier when you understand what a split does, I couldn’t figure it out because I didn’t know what it meant or how to implement it so thank you

[damian]

great video, I did not know that the variable "result" could be made repeatedly this way in conditionals. My solution was:

def main():
exp = input("Expression: ")
x, y, z = exp.split(" ")
xf = float(x)
zf = float(z)

if y == "+":
print (round((xf + zf), 1 ))
elif y == "-":
print (round((xf - zf), 1 ))
elif y == "*":
print (round((xf*zf), 1 ))
else:
print (round((xf/zf), 1 ))

main()

[MuhammadIbrahim-mghx]

My solution:

# Get the expression
x, y, z = input("Expression: ").strip().split()

# Change type of variable x and z
x = float(x)
z = float(z)

# Perform the operations
match y:
case "+":
print(x + z)
case "-":
print(x - z)
case "/":
print(x / z)
case "*":
print(x * z)

[johncheriton]

Perfect! I could NOT work out how to solve this problem but now it is all clear. Thank-you.

[punkguy]

thank you for the new perspective. love how your way is so easy to follow!

def main():
expression = input("Expression: ")

x = float(expression.split()[0])
y = expression.split()[1]
z = float(expression.split()[2])

if y == "+":
print(x + z)
elif y == "-":
print(x - z)
elif y == "*":
print(x * z)
elif y == "/":
print(x / z)

main()

[EasyBeezy-coding]

my approach is using the eval() function which evaluates the expression, this saved me many lines of code and passed the test
x=input("what's x? ")

result=float(eval(x))
print(result)

[junemiabba]

m = input("enter an arithmatic expression ")

print(round(float(eval(m)), 1))
This works too!

[hitechpanchal]

ah... there is a bug in the code in the division section. There needs to be a condition to check the Z!=0 if y is '/'. It is specified as a condition in description it self.

For instance, if the user inputs 1 + 1, your program should output 2.0. Assume that, if y is /, then z will not be 0.

Using a match case should take care of this.

if y == '+' or y == '-' or y == '*':

match y:
code the conditions

elif y == '/' and z != 0:
match y:
case '/':
ans = float(x)/float(z)

[muratozdemir]

Thank you, I was a bit confused with the split method, you brightened my day up

[studywithshin]

I didn't know how to apply split() for this problem. Thank you.

[Noah-lklb]

This is how i solved it. Hope it helps

expression = input("Expression: ").casefold().strip()
x, y, z = expression.split(" ")

num1 = int(x)
num2 = int(z)

add = num1 + num2
subtract = num1 - num2
divide = num1 / num2
multiply = num1 * num2

if "+" in expression:
print(float(add))

elif "-" in expression:
print(float(subtract))

elif "/" in expression:
print(float(divide))

elif "*" in expression:
print(float(multiply))

else:
print("Error: Missing expression")

I think there are some unnecessary lines but it passed all checks

[khunter]

Exactly what I needed. Thank you so much

[tejni]

.strip() gets rid of the spaces at the start and end of the input. but what if the input has spaces inbetween. what if the user input 1+1 with no spaces, instead of 1 + 1 like the problem offers? I tried .remove(" ", "") but then it doesn't do the split correctly and errors.

[ophelia]

thank u for this! i'm new to python and coding in general and i used the "if "+" in y print (x + y) method haha. it worked just fine but it was definitely beneficial to see it done this way, it makes more sense lol<3

[yuyum]

I got the basic code right but had a hard time printing because I made a def for it and returned for example x + y instead of just printing it.
This one was the hardest for me in problem set 1

[TrueJamo]

You got the right results to pass the check but it says in the instructions x and z need to be integers. Later on when getting the answer is when they get converted to a float.

[mehdisheriff]

I did something similar however not quite the same. I went with the approach of rather than calculating for result, I put print(new_x + new_y) of course replacing the operator as required.

I also used if, Élif and else since they only required the 4 operators. However if this were to be more operators, your approach of only if makes a lot more sense

[senisneru]

thank you for the detailed explanation!!
my solutions looks like that:

x, y, z = input("arithmetic expression: ").split(" ")

if y == "+":
print(float(x) + float(z))
elif y == "-":
print(float(x) - float(z))
elif y == "*":
print(float(x) * float(z))
elif y == "/":
print(float(x) / float(z))

[mohamadmovahed-dpjo]

That is very very good vidio
Thanks bot this vidio🎉

[tanishq]

very challenging ques, split holded me down soo bad😂😂😂