GCD and LCM Euclidean Algorithm in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return the greatest common divisor (GCD) of two numbers using the Euclidean algorithm.

DSA Python

def gcd(a, b):
    while b != 0:
        a, b = b, a [1] b
    return a

Drag options to blanks, or click blank then click option'

A%

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or subtraction instead of the remainder operator.

Using multiplication which does not help find the GCD.

The Euclidean algorithm uses the remainder operator % to find the GCD by repeatedly replacing a with b and b with a % b until b becomes zero.

2fill in blank

medium

Complete the code to calculate the least common multiple (LCM) of two numbers using their GCD.

DSA Python

def lcm(a, b):
    return (a * b) // [1](a, b)

Drag options to blanks, or click blank then click option'

Amax

Bmin

Cabs

Dgcd

Attempts:

3 left

💡 Hint

Common Mistakes

Using max or min instead of gcd.

Forgetting to use integer division //.

The LCM of two numbers can be found by dividing the product of the numbers by their GCD.

3fill in blank

hard

Fix the error in the recursive GCD function by completing the return statement.

DSA Python

def gcd_recursive(a, b):
    if b == 0:
        return a
    else:
        return gcd_recursive(b, a [1] b)

Drag options to blanks, or click blank then click option'

A+

B%

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or subtraction instead of the remainder operator.

Using multiplication which is incorrect here.

The recursive Euclidean algorithm calls itself with b and the remainder of a % b until b is zero.

4fill in blank

hard

Fill both blanks to create a function that returns a dictionary with GCD and LCM of two numbers.

DSA Python

def gcd_lcm(a, b):
    gcd_value = gcd(a, b)
    lcm_value = (a * b) [1] gcd_value
    return {'gcd': gcd_value, 'lcm': lcm_value}

Drag options to blanks, or click blank then click option'

A//

B%

C+

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using multiplication instead of division for LCM.

Forgetting to close the dictionary properly.

The LCM is calculated by dividing the product of a and b by their GCD using integer division //. The dictionary is closed with a }.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps numbers to their GCD with a fixed number.

DSA Python

fixed_num = 12
result = [1]: gcd([2], fixed_num) for [3] in range(1, 6)}

Drag options to blanks, or click blank then click option'

Anum

Bfixed_num

Ci

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names for key and loop variable.

Using fixed_num as the loop variable.

The dictionary comprehension uses num as the key, calls gcd(num, fixed_num), and iterates over num in the range 1 to 5.