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

**(Select all that apply.)** Which options are valid palindromes that can be made using the letters in the string given below?

string = “abbjhhrrssS”

(Select all that apply.) Which options are valid palindromes that can be made using the letters in the string given below?
string = “abbjhhrrssS”

**(Select all that apply.)** Which options are valid palindromes that can be made using the letters in the string given below?

string = "abbbhhejjssktaoop"

(Select all that apply.) Which options are valid palindromes that can be made using the letters in the string given below?
string = “abbbhhejjssktaoop”

What is the length of the longest palindrome that you can make using the letters in the string below?

string = "abccccdddeeeeeeff"

What is the length of the longest palindrome that you can make using the letters in the string below?
string = “abccccdddeeeeeeff”

What is the length of the longest palindrome that you can make using the letters in the string below?

string = "xyyyyxxz"

What is the length of the longest palindrome that you can make using the letters in the string below?
string = “xyyyyxxz”

Longest Palindrome

Longest Palindrome

# 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: `longest_palindrome`\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 `longest_palindrome` 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 `longest_palindrome`.\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) `longest_palindrome`. \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) `longest_palindrome`. \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
 """
 import collections

 def longest_palindrome_eval(s):
 # Create a Counter object to count character occurrences
 char_count = collections.Counter(s)
 
 # Initialize a variable to keep track of the longest palindrome length
 longest_length = 0
 
 # Iterate through the character counts
 for count in char_count.values(): # Use values() instead of itervalues()
 longest_length += count // 2 * 2
 
 # Check if there are any characters with odd counts (can be placed in the middle of the palindrome)
 if longest_length < len(s):
 longest_length += 1
 
 return longest_length

 expected = longest_palindrome_eval(self.__inputs[0])
 # 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 longest_palindrome(s):

    # Replace this placeholder return statement with your code
    return -1


PrivateTestCases.yaml

testcases:
  - name: "testcase 1"
    inputs:
    - 1 : "opinion"
    output:
    - 1 : 7

  - name: "testcase 2"
    inputs:
    - 1: "cool"
    output:
    - 1 : 3

  - name: "testcase 3"
    inputs:
    - 1 : "GooooooOOOOODdddD"
    output:
    - 1 : 15
    
  - name: "testcase 4"
    inputs:
    - 1: "REaccaR"
    output:
    - 1 : 7

  - name: "testcase 5"
    inputs:
    - 1 : "AbcDeFGhAachDeFG"
    output:
    - 1 : 15

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

def validate_inputs(self) -> None:
 """
 Validate the string s based on the given constraints.
 Store the result using self.store_result(error_msg, status).
 return: void
 """
 s = self.__inputs[0]

 if not (1 <= len(s) <= 2000):
 self.store_result("String length should be in the range 1 ≤ s.length ≤ 2000", ValidationFunction.FAIL)
 return

 elif not all(char.isalpha() and ord('a') <= ord(char.lower()) <= ord('z') for char in s):
 self.store_result("String s should consist of lowercase and/or uppercase English letters only", ValidationFunction.FAIL)
 return

 else:
 self.store_result("", ValidationFunction.PASS)

Try to solve the Longest Palindrome problem.

Hash Maps

Knowing What to Track

Top K Elements

Heaps

Conclusion

Longest Palindrome

Statement

Examples

Understand the problem

Figure it out!

Try it yourself