Learn and practice the Hash Maps, Knowing What to Track, Top K Elements, and the Heaps patterns to solve coding interview problems.

Grokking Grind 75 in Python: Mastery through Coding Patterns

Efficient data management, information tracking, element identification, and value optimization are crucial to problem-solving, particularly for challenges that involve handling, analyzing, and extracting meaningful insights from data. This module teaches essential coding patterns for all such coding challenges. It covers Hash Maps for storing and retrieving data, Knowing What to Track for identifying and managing key information, Top K Elements for extracting significant data points, and Heaps for efficiently handling extreme values in datasets. These techniques are valuable for solving various data-centric challenges, optimizing algorithms, and data manipulation.

Heaps, Hashing and Tracking

# Statement
Given two strings, `str1` and `str2`, check whether `str2` is an anagram of `str1`.

An **anagram** is a word or phrase created by rearranging the letters of another word or phrase while utilizing each of the original letters exactly once.

**Constraints:**

- $1 \leq$ `str1.length`, `str2.length` $\leq 10^3$

- `str1` and `str2` consist of only 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’s the correct output for the following inputs?

`str1` = "heart"

`str2` = "earth"


What’s the correct output for the following inputs?
<code>str1</code> = “heart”
<code>str2</code> = “earth”

What’s the correct output for the following inputs?

`str1` = "ram"

`str2` = "car"

What’s the correct output for the following inputs?
<code>str1</code> = “ram”
<code>str2</code> = “car”

What’s the correct output for the following inputs?

`str1` = "creative"

`str2` = "reactive"

What’s the correct output for the following inputs?
<code>str1</code> = “creative”
<code>str2</code> = “reactive”

Valid Anagram

Valid Anagram

# 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.


# Quick Fix\nYou are Edward, a Senior Software Engineer who specializes in coding interview patterns, data structures and algorithms, and is great at debugging issues in code.\n\n- Edward, please keep in mind that you do not have to print the data of the placeholders. Also, do not mention anything about yourself.\n\nEdward, you are given the following data in the placeholders:\n- Function name: `is_anagram`\n- Candidate's submitted solution code: USER_CODE\n- Error: ERROR_DESCRIPTION\n- Failed test case: FAILED_TEST_CASE\n- Coding language: `Python`\n\n- Edward, your task is to understand the type of error that is occurring in the coding language provided.\n- Once you've understood the error as per the error’s description, and why the test case failed, you will suggest how the candidate can improve their solution code to fix the error.\n- Edward, you will not give the corrected code, just a hint on what the error tells, and how to fix it.\n- Edward, please limit your response strictly to 100 words. No more words than the limit.

# Review Code\nEdward, your current task is to review the `is_anagram` function(s) and the other function(s) invoked in it/them.\n\n-Take your time and review the candidate's solution code.\n- Do not review any extra/helper files or functions not invoked in the solution function `is_anagram`.\n- Do not review the code of data structure 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. \n- Also, if the solution code doesn’t use the coding pattern stated above, then please encourage the candidate to reattempt the problem using that pattern corectly.

# Review time complexity\n- Please provide a brief time complexity analysis of the function(s) `is_anagram`. \n- While calculating time complexity, include the time complexity of built-in Python functions invoked by the code. \n- The answer should be to the point in approximately 60 words.

# Review space complexity\n- Please provide a brief space complexity analysis of the function(s) `is_anagram`. \n- While calculating space complexity, include the space complexity of built-in Python functions invoked by the code. \n- 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). \n- The answer should be to the point in approximately 60 words.

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 is_anagram_eval(str1, str2):
            if len(str1) != len(str2):
                return False
            
            table = {}
            
            for i in str1:
                if i in table:
                    table[i] += 1
                
                else:
                    table[i] = 1
            
            for i in str2:
                if i in table:
                    table[i] -= 1
                
                else:
                    return False
            
            for key in table:
                if table[key] != 0:
                    return False
            
            return True

        expected = is_anagram_eval(self.__inputs[0], self.__inputs[1])

        # multiple outputs will be added at each index respectively for a single test_case
        expected_outputs = [] 
        # store the 1st expected output that should be displayed to the user 

        if json.dumps(expected) == json.dumps(self.__actual_outputs[0]):
            expected_outputs.append(expected)
            self.__edu_result.store_result(expected_outputs, TestCaseResult.PASS)
        else:
            expected_outputs.append(expected)
            self.__edu_result.store_result(expected_outputs, TestCaseResult.FAIL)

        return self.__edu_result

def is_anagram(str1, str2):

    # Replace this placeholder return statement with your code
    return False


valid_anagram.yaml

testcases:
  - name: "testcase 1"
    inputs:
    - 1 : "anagram"
    - 2 : "nagaram"
    output: 
    - 1 : True
  - name: "testcase 2"
    inputs:
    - 1: "spare"
    - 2: "pears"
    output:
    - 1 : True
  - name: "testcase 3"
    inputs:
    - 1: "heart"
    - 2: "earth"
    output:
    - 1 : True
  - name: "testcase 4"
    inputs:
    - 1: "super"
    - 2: "upper"
    output:
    - 1 : False
  - name: "testcase 5"
    inputs:
    - 1: "triangle"
    - 2: "integral"
    output:
    - 1 : True


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

def validate_inputs(self) -> None:
 """
 Validate str1 and str2 based on the given constraints.
 Store the result using self.store_result(error_msg, status).
 return: void
 """
 str1 = self.__inputs[0]
 str2 = self.__inputs[1]

 if not (1 <= len(str1) <= 10**3 and 1 <= len(str2) <= 10**3):
 self.store_result("String lengths should be in the range 1 <= str1.length, str2.length <= 10^3", ValidationFunction.FAIL)
 return

 elif not all(char.islower() for char in str1):
 self.store_result("String 'str1' should consist of only lowercase English letters", ValidationFunction.FAIL)
 return

 elif not all(char.islower() for char in str2):
 self.store_result("String 'str2' should consist of only lowercase English letters", ValidationFunction.FAIL)
 return

 else:
 self.store_result("", ValidationFunction.PASS)

Hash Maps

Knowing What to Track

Top K Elements

Heaps

Conclusion

Valid Anagram

Statement

Examples

Understand the problem

Figure it out!

Try it yourself