Roman to Integer Conversion in DSA Python - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the result variable to zero.

DSA Python

def roman_to_int(s):
    result = [1]
    return result

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

A0

B1

CNone

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing result with 1 instead of 0

Using an empty string instead of a number

We start counting the integer value from zero before processing the Roman numeral string.

2fill in blank

medium

Complete the code to get the integer value for the current Roman numeral character.

DSA Python

def roman_to_int(s):
    roman_map = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
    result = 0
    for i in range(len(s)):
        value = roman_map[[1]]
    return result

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

Ai

Bs[i]

Cs

Droman_map[i]

Attempts:

3 left

💡 Hint

Common Mistakes

Using i instead of s[i]

Trying to use roman_map[i] which is invalid

We use s[i] to get the character at position i in the string s to look up its integer value.

3fill in blank

hard

Fix the error in the condition to check if the current value is less than the next value.

DSA Python

def roman_to_int(s):
    roman_map = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
    result = 0
    for i in range(len(s)):
        value = roman_map[s[i]]
        if i + 1 < len(s) and value [1] roman_map[s[i + 1]]:
            result -= value
        else:
            result += value
    return result

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

A>

B!=

C==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<'

Using '==' or '!=' which are incorrect here

If the current value is less than the next value, we subtract it according to Roman numeral rules.

4fill in blank

hard

Fill both blanks to complete the loop and return statement correctly.

DSA Python

def roman_to_int(s):
    roman_map = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
    result = 0
    for [1] in range(len(s)):
        value = roman_map[s[i]]
        if i + 1 < len(s) and value < roman_map[s[i + 1]]:
            result -= value
        else:
            result += value
    return [2]

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

Ai

Bs

Cresult

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 's' as loop variable instead of 'i'

Returning 'value' or 's' instead of 'result'

The loop variable is 'i' to index the string, and we return the final integer 'result'.

5fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps Roman numerals to their integer values for given keys and values.

DSA Python

keys = ['I', 'V', 'X', 'L', 'C', 'D', 'M']
values = [1, 5, 10, 50, 100, 500, 1000]
roman_map = { [2] : [1] for [3] in zip(keys, values)}

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

A{

Bv

Ck

D}

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'k' for values or 'v' for keys

Not starting with '{' for dictionary comprehension

We start the dictionary with '{', use 'v' for values, 'k' for keys, and close with '}' (already in code).