Learn and practice the Cyclic Sort and Topological Sort patterns to solve coding interview problems.

Speedrun the Netflix Coding Interview: Top Problems in Python

This module will focus on two advanced sorting algorithms, Cyclic Sort and Topological Sort. These are often used in coding interviews as a way to distinguish between average and outstanding candidates. Cyclic Sort may only be used if the input list meets certain criteria, and in those situations, it’s the most efficient sorting algorithm possible. Topological Sort utilizes graph-based algorithms to deal with partially ordered elements. This module teaches us to recognize whether either of these advanced sorting techniques is applicable, as well as how to use them to solve the given problem.

Advanced Sorting Techniques

# Statement

You're given a list of words with lowercase English letters in a different order,  written in an alien language. The order of the alphabet is some permutation of lowercase letters of the English language.

We have to return TRUE if the given list of words is sorted lexicographically in this alien language.

**Constraints:**

- $1 \leq$ `words.length` $\leq 10^3$
- $1 \leq$ `words[i].length` $\leq 20$
- `order.length` $== 26$
- All the characters in `words[i]` and `order` are lowercase English letters.

# Examples


# Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:


What is the output if the following list of words and order are given as input?

words = ["alpha", "bravo", "charlie", "delta"]

order = "hlabcdgiwjkmnopqerstfuvxyz"

What is the output if the following list of words and order are given as input?
words = [“alpha”, “bravo”, “charlie”, “delta”]
order = “hlabcdgiwjkmnopqerstfuvxyz”

What is the output if the following list of words and order are given as input?

words = ["wrt", "wrf", "er", "ett", "rftt"]

order = "hlabcdgiwjkmnopqerstfuvxyz"

What is the output if the following list of words and order are given as input?
words = [“wrt”, “wrf”, “er”, “ett”, “rftt”]
order = “hlabcdgiwjkmnopqerstfuvxyz”

What is the output if the following list of words and order are given as input?

words = ["hello", "to", "my", "world"]

order = "hlabcdefgijkmnopqrstuvwxyz"

What is the output if the following list of words and order are given as input?
words = [“hello”, “to”, “my”, “world”]
order = “hlabcdefgijkmnopqrstuvwxyz”

What is the output if the following list of words and order are given as input?

words = ["you", "are", "a", "great", "human"]

order = "abcdefghijklmnopqrstuvwxyz"

What is the output if the following list of words and order are given as input?
words = [“you”, “are”, “a”, “great”, “human”]
order = “abcdefghijklmnopqrstuvwxyz”

Verifying an Alien Dictionary

Verifying an Alien Dictionary

# Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

# Try it yourself

Implement your solution in the following coding playground:


Help me debug only the function Verifying an Alien Dictionary . . I don't need the corrected code.I don't want explanations or code review. Just provide me the exact and to-the-point error that helps me run the code successfully on the test cases provided.

Please help me understand why this code failed for the last failed test case. Don't give me the corrected code. . If yes, then Just provide me the exact and to-the-point error that helps me run the code successfully on the test cases provided.

Your current task is to review only the verify_alien_dictionary function and the other function(s) invoked in it/them. Do not review extra/helper files or functions not invoked in the solution function verify_alien_dictionary. Do not review the code of data structures objects instantiated like a binary tree, linked list, trie, union find, etc., in the solution functions. Just review the solution/algorithm function of the problem. Also, Answer the following questions: Is the Topological Sort pattern used? Take your time and review the code.

Please provide a brief time complexity analysis of the function verify_alien_dictionary. While calculating time complexity, include the time complexity of built-in Python functions invoked by the code. The Answer should be to the point and in a few lines.

Please provide a brief Space complexity analysis of the function verify_alien_dictionary. While calculating space complexity, include the space complexity of built-in Python functions invoked by the code. Do not include the space used for the input parameters and the space used for just returning an output(not used as a scratch space). The Answer should be to the point and in a few lines

def evaluate_results(self) -> object:
        """
        self.__inputs is the list of inputs that are passed as input to function
        self.__actual_output is a list of outputs that is produced by the learner's code
        return : self.__edu__result object
        """
        def verify_alien_dictionary(words, order):
            if len(words) == 1:
                return True
            
            order_map = {}
            
            for index, val in enumerate(order):
                order_map[val] = index
            
            for i in range(len(words) - 1):
                for j in range(len(words[i])):
                    if j >= len(words[i + 1]):
                        return False
                    
                    if words[i][j] != words[i + 1][j]:
                        if order_map[words[i][j]] > order_map[words[i + 1][j]]:
                            return False
                        break
            
            return True

        # multiple outputs will be added at each index respectively for a single test_case
        expected=verify_alien_dictionary(self.__inputs[0] ,self.__inputs[1])
        expected_outputs = [] 
        # store the 1st expected output that should be displayed to the user 
        expected_outputs.append(expected)

        if json.dumps(expected) == json.dumps(self.__actual_outputs[0]):
            self.__edu_result.store_result(expected_outputs, TestCaseResult.PASS)
        else:
            self.__edu_result.store_result(expected_outputs, TestCaseResult.FAIL)

        return self.__edu_result

def verify_alien_dictionary(words, order):
  
    # Replace this placeholder return statement with your code
    return False

PrivateTestCases.yaml

testcases:
  - name: "testcase 1"
    inputs:
    - 1 : ["h"]
    - 2 : hlabcdefgijkmnopqrstuvwxyz
    output: 
    - 1 : True
  - name: "testcase 2"
    inputs:
    - 1: ["martian"]
    - 2: mabcdefghijklnopqrstuvwxyz
    output:
    - 1 : True
  - name: "testcase 3"
    inputs:
    - 1: ["passengers", "to", "the", "unknown"]
    - 2: ptuabcdefghijklmnoqrsvwxyz
    output:
    - 1 : False
  - name: "testcase 4"
    inputs:
    - 1: ["jupyter", "ascending"]
    - 2: jabcdefghiklmnopqrstuvwxyz
    output:
    - 1 : True
  - name: "testcase 5"
    inputs:
    - 1: ["marvel", "marvellous"]
    - 2: marvelbcdfghijknopqstuwxyz
    output:
    - 1 : True


def sum(input_1, input_2):
    return input_1+input_2

def validate_inputs(self) -> None:
 """
 self.__inputs is the list of inputs that are passed as input to the function
 store the result using the self.store_result(error_msg, status)
 return: void
 """
 min_word_count = 1
 max_word_count = 1000
 min_word_length = 1
 max_word_length = 20
 valid_order_length = 26

 words = self.__inputs[0]
 order = self.__inputs[1]
 def is_valid_1d_array(arr):
 if not isinstance(arr, list):
 return False # Not a valid 1D array if it's not a list
 
 return all(isinstance(elem, str) and not isinstance(elem, bool) for elem in arr)

 if not is_valid_1d_array(words):
 self.store_result(("Invalid test case."), ValidationFunction.FAIL)
 # Inputs can be accessed using self.__inputs starting from 0 to len(self.__inputs) - 1
 elif any(num is None for num in words):
 self.store_result ("Not a valid test case", ValidationFunction.FAIL)
 elif not (min_word_count <= len(words) <= max_word_count):
 self.store_result("The number of words should be between 1 and 10^3.", ValidationFunction.FAIL)
 elif any(not isinstance(word, str) for word in words):
 self.store_result("Each 'word' should be a string.", ValidationFunction.FAIL)
 elif any(not (min_word_length <= len(word) <= max_word_length) for word in words):
 self.store_result("Each 'word' should have a length between 1 and 20.", ValidationFunction.FAIL)
 elif any(not word.islower() for word in words):
 self.store_result("Each 'word' should be a lowercase English word.", ValidationFunction.FAIL)
 elif any(not isinstance(char, str) or not char.islower() for char in order):
 self.store_result("Each character in 'order' should be a lowercase English letter.", ValidationFunction.FAIL) 
 elif len(order) != valid_order_length:
 self.store_result("The length of 'order' should be 26.", ValidationFunction.FAIL)
 else:
 self.store_result("", ValidationFunction.PASS)

Try to solve the Verifying an Alien Dictionary problem.

Cyclic Sort

Topological Sort

Conclusion

Verifying an Alien Dictionary

Statement

Examples

Understand the problem

Figure it out!

Try it yourself