feat(algorithms, dynamic-programming): counting bits #153
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BrianLusina
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Algorithm
📝 WalkthroughWalkthroughAdds Counting Bits, K Closest Elements, Merge K Sorted Lists, and Paint House algorithm modules with READMEs and unit tests; implements Changes
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Actionable comments posted: 4
🤖 Fix all issues with AI agents
In `@algorithms/dynamic_programming/countingbits/README.md`:
- Around line 54-56: The sentence starting "in the binary representation of i is
that number plus 1" is incomplete; rewrite it to include the missing subject so
it reads clearly (e.g., "The number of 1s in the binary representation of i is
that number plus 1 if the rightmost bit is 1.") — update the README.md sentence
that references the variable i and the rightmost bit to explicitly state "the
number of 1s" (or equivalent) and ensure the following sentence about checking
odd/even ties back to that clarified phrasing.
In `@algorithms/heap/kclosestelements/README.md`:
- Around line 3-5: Fix the minor grammar in the problem description: change the
phrase "Return these elements in array" to "Return these elements in an array"
in the README description (the sentence that starts "Return these elements...")
so the wording is correct and reads "Return these elements in an array, sorted
in ascending order."
In `@algorithms/heap/mergeksortedlists/__init__.py`:
- Around line 45-46: Fix the typo in the inline comment that reads "We check if
the element index is less than the current list it can be found in. This means
that there are still other elements withing this list" by changing "withing" to
"within" so the comment now reads "...there are still other elements within this
list"; update the comment near the merge logic in mergeksortedlists/__init__.py
where that sentence appears.
In `@algorithms/heap/mergeksortedlists/test_merge_k_sorted_lists.py`:
- Line 16: Rename the test class from MegeKListsTestCase to MergeKListsTestCase:
update the class declaration "class MegeKListsTestCase(unittest.TestCase):" to
"class MergeKListsTestCase(unittest.TestCase):" and update any references to
MegeKListsTestCase within the test file (or other test modules) to the corrected
name so unittest discovery and any imports/subclasses continue to work.
🧹 Nitpick comments (4)
algorithms/dynamic_programming/countingbits/README.md (1)
19-19: Add language specifier to fenced code block.The code block is missing a language specifier. For consistency with Example 1 (line 8), add
textafter the opening fence.Proposed fix
-``` +```text Example 2:algorithms/dynamic_programming/countingbits/__init__.py (1)
16-17: Minor grammar fix in comment.The comment is slightly unclear. Consider rephrasing for better readability.
Proposed fix
- # this can also be solved as which is faster in Python + # Alternative using bitwise ops (may be faster): # dp[i] = dp[i >> 1] + (i & 1)algorithms/heap/kclosestelements/__init__.py (1)
5-5: Add return type annotation and docstring.The function is missing a return type annotation and docstring for consistency with the codebase (e.g.,
merge_k_listsin this PR has both).♻️ Suggested improvement
-def k_closest(nums: List[int], k: int, target: int): +def k_closest(nums: List[int], k: int, target: int) -> List[int]: + """ + Returns the k elements from nums closest to target. + Args: + nums: List of integers + k: Number of closest elements to return + target: Target value to measure distance from + Returns: + List of k integers closest to target, sorted in ascending order + """ heap = []algorithms/heap/kclosestelements/test_find_k_closest_elements.py (1)
6-13: Consider adding edge case tests.The current test cases cover good scenarios, but consider adding edge cases for robustness:
- Empty array:
([], 0, 5, [])kequals array length:([1, 2, 3], 3, 2, [1, 2, 3])- Single element:
([5], 1, 10, [5])- Negative numbers:
([-5, -3, 0, 2], 2, -1, [-3, 0])
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📒 Files selected for processing (13)
DIRECTORY.mdalgorithms/dynamic_programming/climb_stairs/README.mdalgorithms/dynamic_programming/climb_stairs/__init__.pyalgorithms/dynamic_programming/climb_stairs/test_climb_stairs.pyalgorithms/dynamic_programming/countingbits/README.mdalgorithms/dynamic_programming/countingbits/__init__.pyalgorithms/dynamic_programming/countingbits/test_counting_bits.pyalgorithms/heap/kclosestelements/README.mdalgorithms/heap/kclosestelements/__init__.pyalgorithms/heap/kclosestelements/test_find_k_closest_elements.pyalgorithms/heap/mergeksortedlists/README.mdalgorithms/heap/mergeksortedlists/__init__.pyalgorithms/heap/mergeksortedlists/test_merge_k_sorted_lists.py
🧰 Additional context used
🧬 Code graph analysis (2)
algorithms/dynamic_programming/countingbits/test_counting_bits.py (1)
algorithms/dynamic_programming/countingbits/__init__.py (1)
count_bits(4-20)
algorithms/heap/kclosestelements/test_find_k_closest_elements.py (1)
algorithms/heap/kclosestelements/__init__.py (1)
k_closest(5-18)
🪛 LanguageTool
algorithms/dynamic_programming/countingbits/README.md
[style] ~67-~67: Using many exclamation marks might seem excessive (in this case: 10 exclamation marks for a text that’s 2311 characters long)
Context: ...solutions/counting_bits_solution_1.png) 
🪛 markdownlint-cli2 (0.18.1)
algorithms/dynamic_programming/countingbits/README.md
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DIRECTORY.md
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🔇 Additional comments (12)
algorithms/dynamic_programming/countingbits/__init__.py (1)
4-20: LGTM!The dynamic programming implementation is correct and efficient:
- O(n) time and space complexity
- Properly handles the base case (dp[0] = 0)
- The recurrence relation
dp[i] = dp[i // 2] + (i % 2)correctly leverages the relationship between a number and its right-shifted formalgorithms/dynamic_programming/countingbits/test_counting_bits.py (2)
6-13: LGTM!Good test coverage with parameterized tests:
- Edge case
n=0is covered- Multiple input sizes tested
- Expected values are correct (verified against binary representations)
16-20: LGTM!Clean test structure using
parameterized.expandfor data-driven testing. The assertion correctly compares expected and actual results.DIRECTORY.md (1)
58-61: LGTM!The directory structure updates correctly reflect the new algorithm implementations. The static analysis indentation warnings (MD007) are false positives — the indentation style used here is consistent with the rest of the file throughout.
Also applies to: 145-146, 153-154
algorithms/heap/kclosestelements/__init__.py (1)
8-18: LGTM!The max-heap approach using negative differences is a clean and efficient O(n log k) solution. The logic correctly maintains the k closest elements and returns them sorted.
algorithms/heap/mergeksortedlists/__init__.py (2)
14-20: LGTM!Good defensive programming with proper input validation handling both
[]and[[]]cases.
30-53: LGTM!Clean implementation of the k-way merge pattern. The heap tuple structure
(value, list_index, element_index)correctly prioritizes by value, and the logic properly tracks positions within each list.algorithms/heap/mergeksortedlists/test_merge_k_sorted_lists.py (1)
6-13: LGTM!Good test coverage including edge cases (empty inputs, single list) and scenarios with negative numbers and duplicates.
algorithms/heap/mergeksortedlists/README.md (1)
1-18: LGTM!Clear documentation with a helpful example showing both array and linked-list notation. The implementation uses arrays (
List[List[int]]) which is a valid representation for this problem.algorithms/heap/kclosestelements/README.md (1)
7-29: Documentation examples are clear and helpful.The examples effectively illustrate the problem with both a detailed explanation (first example) and a concise output (second example).
algorithms/heap/kclosestelements/test_find_k_closest_elements.py (2)
1-4: LGTM!Imports are appropriate. Using
parameterizedfor test case expansion is a clean approach for testing multiple inputs.
16-22: Test implementation is clean and follows best practices.Good use of
parameterized.expandfor data-driven testing. The assertion correctly compares expected vs actual results.
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Actionable comments posted: 1
🤖 Fix all issues with AI agents
In `@algorithms/heap/kclosestelements/README.md`:
- Around line 17-18: Remove the redundant "Explanation:" text in the paragraph
that begins "Explanation: -1 is 2 away..." so it doesn't duplicate the section
header "Explanation"—keep the section header "Explanation" and change the
paragraph to start directly with "-1 is 2 away from 1, 0 is 1 away from 1, and 1
is 0 away from 1. All other elements are more than 2 away."
🧹 Nitpick comments (1)
algorithms/heap/kclosestelements/README.md (1)
14-27: Standardize "Output" formatting.The first example uses "Output" without a colon (line 14), while the second example uses "Output:" with a colon (line 27). Consider standardizing this for consistency.
📝 Suggested fix
-Output +Output: [-1, 0, 1]
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- algorithms/heap/mergeksortedlists/test_merge_k_sorted_lists.py
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Actionable comments posted: 4
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⚠️ Outside diff range comments (1)
DIRECTORY.md (1)
58-77: PR scope exceeds the stated objective.The PR title indicates this adds only "counting bits", but the changes add at least 5 algorithm modules:
- Climb Stairs (lines 58-59)
- Counting Bits (lines 60-61)
- Paint House (lines 76-77)
- K Closest Elements (lines 147-148)
- Merge K Sorted Lists (lines 155-156)
Additionally, the PR description claims "single algorithm file changed", but this appears to add multiple distinct algorithms across different categories (Dynamic Programming and Heap).
Consider splitting this into separate PRs for each algorithm to:
- Make reviews more focused and manageable
- Enable easier rollback if issues arise
- Improve git history clarity
- Follow the single-responsibility principle
Also applies to: 147-156
🤖 Fix all issues with AI agents
In `@algorithms/dynamic_programming/painthouse/README.md`:
- Around line 75-85: Fix the typos in the README's recurrence explanation:
change `prev_min_cost_gree` to `prev_min_cost_green` in the red calculation,
change the green-line suffix `+ cost_blue` to `+ cost_green`, and correct
`prev_mins_cost_red` to `prev_min_cost_red`; ensure all three lines consistently
reference prev_min_cost_red, prev_min_cost_blue, prev_min_cost_green and their
corresponding cost_red, cost_blue, cost_green symbols.
In `@DIRECTORY.md`:
- Around line 147-148: Update the inconsistent Heap section entries: rename the
headings/text "Kclosestelements" to "K Closest Elements" and "Mergeksortedlists"
to "Merge K Sorted Lists" wherever they appear (including the two occurrences
around the referenced lines), and update the corresponding Markdown link text
and directory/file paths to follow the space-separated heading and snake_case
filename convention (e.g., k_closest_elements and merge_k_sorted_lists) so link
targets and displayed names match the repository naming style.
- Around line 76-77: Update the directory entry "Painthouse" to the
space-separated, consistent name "Paint House" (or "Paint Houses" to match
test_min_cost_to_paint_houses.py) and rename the corresponding folder identifier
from painthouse to paint_house so it follows the project's naming convention;
update any references to the test file test_min_cost_to_paint_houses.py or its
link text to match the new display name to avoid mismatches.
- Around line 60-61: Rename the "Countingbits" entry to "Counting Bits" to match
the space-separated naming used by other Dynamic Programming entries, change the
nested list indentation to 2 spaces (not 4-6) so it aligns with Markdown best
practices, and update the directory/module name from countingbits to
counting_bits (and the repo link path if necessary) to follow Python naming
conventions; ensure the link text and target reflect the new names.
🧹 Nitpick comments (1)
algorithms/dynamic_programming/painthouse/__init__.py (1)
4-14: Consider adding doctests per PR checklist.The PR checklist indicates that "all functions include doctests that pass automated testing." This function lacks doctests. Adding doctests would also serve as inline documentation.
📝 Suggested doctest examples
def min_cost_to_paint_houses_alternate_colors(costs: List[List[int]]) -> int: """ Finds the minimum cost to paint houses in a street without repeating colors consecutively Args: costs(list): Costs of painting houses as a 2D list Returns: int: minimum cost of painting houses + + >>> min_cost_to_paint_houses_alternate_colors([[8, 4, 15], [10, 7, 3], [6, 9, 12]]) + 13 + >>> min_cost_to_paint_houses_alternate_colors([[5, 8, 6], [19, 14, 13], [7, 5, 12], [14, 5, 9]]) + 30 + >>> min_cost_to_paint_houses_alternate_colors([]) + 0 """
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DIRECTORY.mdalgorithms/dynamic_programming/painthouse/README.mdalgorithms/dynamic_programming/painthouse/__init__.pyalgorithms/dynamic_programming/painthouse/test_min_cost_to_paint_houses.py
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algorithms/dynamic_programming/painthouse/test_min_cost_to_paint_houses.py (1)
algorithms/dynamic_programming/painthouse/__init__.py (1)
min_cost_to_paint_houses_alternate_colors(4-43)
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algorithms/dynamic_programming/painthouse/README.md
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🔇 Additional comments (3)
algorithms/dynamic_programming/painthouse/test_min_cost_to_paint_houses.py (1)
1-20: LGTM!The test file is well-structured with parameterized test cases that match the examples in the README. The use of
parameterized.expandfor data-driven testing is appropriate.algorithms/dynamic_programming/painthouse/__init__.py (1)
25-43: LGTM!The DP implementation is correct and space-efficient. The algorithm properly ensures no two adjacent houses share the same color by computing each current cost as the minimum of the two non-matching previous costs plus the current color cost.
algorithms/dynamic_programming/painthouse/README.md (1)
1-16: Documentation structure looks good.The problem statement, constraints, and examples are well-documented. Note: The static analysis warnings about reference links on lines 5-7 and 15 are false positives—
[0],[1],[2], and[j]are array index notation, not Markdown reference links.
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Describe your change:
Counting bits
Checklist:
Fixes: #{$ISSUE_NO}.Summary by CodeRabbit
New Features
Documentation
Tests
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