⚡️ Speed up function sorter by 88%

[codeflash-ai]

📄 88% (0.88x) speedup for sorter in codeflash/bubble_sort.py

⏱️ Runtime : 446 milliseconds → 237 milliseconds (best of 39 runs)

📝 Explanation and details

The optimized code implements two key bubble sort optimizations that significantly reduce unnecessary work:

1. Reduced Inner Loop Range: Changed range(len(arr) - 1) to range(len(arr) - i - 1). This eliminates redundant comparisons since bubble sort guarantees that after each outer loop iteration i, the largest i+1 elements are already in their correct positions at the end of the array.

2. Early Exit with Swap Detection: Added a swapped flag that tracks whether any swaps occurred during an inner loop pass. If no swaps happen, the array is already sorted and the algorithm can terminate early via break.

Performance Impact: The line profiler shows the inner loop executed ~12.25M times in the original vs ~4.88M times in the optimized version - a 60% reduction in iterations. This translates to an 88% speedup (446ms → 237ms).

Best Case Scenarios: The optimizations are particularly effective for:

• Already sorted arrays (like test_sorter_large_sorted): Early exit after first pass
• Nearly sorted arrays: Minimal swaps trigger early termination
• Large arrays: The O(n²) → O(n) improvement for best cases becomes more pronounced

The swapping logic and in-place mutation behavior remain identical, ensuring full correctness while dramatically improving performance for common real-world scenarios where data is often partially sorted.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	✅ 3 Passed
🌀 Generated Regression Tests	✅ 56 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	✅ 1 Passed
📊 Tests Coverage	100.0%

⚙️ Existing Unit Tests and Runtime

🌀 Generated Regression Tests and Runtime

from typing import List, Union

# imports
import pytest  # used for our unit tests
from codeflash.bubble_sort import sorter

# unit tests

# --- Basic Test Cases ---

def test_sorter_sorted_list():
    # Already sorted list should remain the same
    arr = [1, 2, 3, 4, 5]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_reverse_list():
    # Reverse sorted list should be sorted
    arr = [5, 4, 3, 2, 1]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_unsorted_list():
    # Random unsorted list
    arr = [3, 1, 4, 2, 5]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_with_duplicates():
    # List with duplicates
    arr = [3, 1, 2, 3, 2]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_floats():
    # List of floats
    arr = [2.2, 1.1, 3.3, 0.0]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_mixed_int_float():
    # List of mixed ints and floats
    arr = [2, 1.5, 3, 0.5]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_single_element():
    # List with one element
    arr = [42]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_two_elements_sorted():
    # Two elements, already sorted
    arr = [1, 2]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_two_elements_unsorted():
    # Two elements, unsorted
    arr = [2, 1]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

# --- Edge Test Cases ---

def test_sorter_empty_list():
    # Empty list should return empty list
    arr = []
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_all_equal():
    # All elements are the same
    arr = [7, 7, 7, 7]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_negative_numbers():
    # List with negative numbers
    arr = [-3, -1, -2, -4]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_mixed_signs():
    # List with positive and negative numbers
    arr = [3, -2, 0, 1, -1]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_and_small_floats():
    # List with very large and very small floats
    arr = [1e10, -1e-10, 5.5, -1e10]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_min_max_int():
    # List with min and max int values
    arr = [2, -2147483648, 2147483647, 0]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_min_max_float():
    # List with min and max float values
    arr = [1.0, float('-inf'), float('inf'), 0.0]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_nan_values():
    # List containing NaN values (should sort but keep NaN at the end)
    import math
    arr = [3, math.nan, 2, 1]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_inf_and_nan():
    # List containing both inf and nan values
    import math
    arr = [math.inf, math.nan, -math.inf, 0]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_mutation():
    # Ensure the original list is mutated (bubble sort is in-place)
    arr = [3, 2, 1]
    sorter(arr)

def test_sorter_mutation_copy():
    # Ensure that passing a copy does not mutate the original
    arr = [3, 2, 1]
    arr_copy = arr.copy()
    codeflash_output = sorter(arr_copy); result = codeflash_output

# --- Large Scale Test Cases ---

def test_sorter_large_sorted_list():
    # Large sorted list
    arr = list(range(1000))
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_reverse_list():
    # Large reverse sorted list
    arr = list(range(999, -1, -1))
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_random_list():
    # Large random list
    import random
    arr = random.sample(range(1000), 1000)
    expected = sorted(arr)
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_duplicates():
    # Large list with many duplicates
    arr = [5]*500 + [3]*250 + [7]*250
    expected = [3]*250 + [5]*500 + [7]*250
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_negative_positive():
    # Large list with negative and positive numbers
    arr = list(range(-500, 500))
    import random
    random.shuffle(arr)
    expected = sorted(arr)
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_floats():
    # Large list of floats
    import random
    arr = [random.uniform(-1000, 1000) for _ in range(1000)]
    expected = sorted(arr)
    codeflash_output = sorter(arr.copy()); result = codeflash_output
    # Compare floats with tolerance
    for a, b in zip(result, expected):
        pass

# --- Determinism Test ---

def test_sorter_determinism():
    # The function should always produce the same result for the same input
    arr = [5, 3, 1, 4, 2]
    codeflash_output = sorter(arr.copy()); result1 = codeflash_output
    codeflash_output = sorter(arr.copy()); result2 = codeflash_output

# --- Type Preservation Test ---

def test_sorter_type_preservation_int():
    # The type of elements should be preserved for ints
    arr = [3, 1, 2]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_type_preservation_float():
    # The type of elements should be preserved for floats
    arr = [3.1, 1.2, 2.3]
    codeflash_output = sorter(arr.copy()); result = codeflash_output
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
from typing import List, Union

# imports
import pytest  # used for our unit tests
from codeflash.bubble_sort import sorter

# unit tests

# ===========================
# BASIC TEST CASES
# ===========================

def test_sorter_basic_sorted():
    # Already sorted list
    arr = [1, 2, 3, 4, 5]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_basic_reverse():
    # Reverse sorted list
    arr = [5, 4, 3, 2, 1]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_basic_unsorted():
    # Unsorted list
    arr = [3, 1, 4, 5, 2]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_basic_duplicates():
    # List with duplicates
    arr = [2, 3, 2, 1, 4]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_basic_floats():
    # List of floats
    arr = [3.2, 1.5, 2.8, 0.9]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_basic_mixed_int_float():
    # List of ints and floats
    arr = [2, 3.5, 1, 4.2]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

# ===========================
# EDGE TEST CASES
# ===========================

def test_sorter_edge_empty():
    # Empty list
    arr = []
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_single_element():
    # Single element list
    arr = [42]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_all_equal():
    # All elements are equal
    arr = [7, 7, 7, 7]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_negative_numbers():
    # List with negative numbers
    arr = [-3, -1, -7, -2]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_mixed_signs():
    # List with negative and positive numbers
    arr = [-2, 4, 0, -5, 3]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_large_and_small_values():
    # List with very large and very small values
    arr = [1e10, -1e10, 0, 1e-10, -1e-10]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_already_sorted_descending():
    # Already sorted descending
    arr = [5, 4, 3, 2, 1]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_two_elements():
    # Two elements, unsorted
    arr = [2, 1]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_two_elements_sorted():
    # Two elements, already sorted
    arr = [1, 2]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_edge_large_float_precision():
    # Floats with very close values
    arr = [1.000001, 1.0000001, 1.0000002]
    codeflash_output = sorter(arr.copy()); result = codeflash_output

# ===========================
# LARGE SCALE TEST CASES
# ===========================

def test_sorter_large_random():
    # Large list of random integers
    import random
    arr = random.sample(range(-1000, 0), 1000)  # 1000 unique integers
    expected = sorted(arr)
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_duplicates():
    # Large list with many duplicates
    arr = [5]*500 + [2]*250 + [9]*250
    expected = sorted(arr)
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_sorted():
    # Large already sorted list
    arr = list(range(1000))
    expected = arr.copy()
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_reverse_sorted():
    # Large reverse sorted list
    arr = list(range(999, -1, -1))
    expected = sorted(arr)
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_floats():
    # Large list of floats
    import random
    arr = [random.uniform(-1000, 1000) for _ in range(1000)]
    expected = sorted(arr)
    codeflash_output = sorter(arr.copy()); result = codeflash_output

def test_sorter_large_negative_and_positive():
    # Large list with negative and positive numbers
    arr = list(range(-500, 500))
    random_arr = arr.copy()
    import random
    random.shuffle(random_arr)
    expected = sorted(random_arr)
    codeflash_output = sorter(random_arr.copy()); result = codeflash_output

# ===========================
# ADDITIONAL EDGE CASES
# ===========================

def test_sorter_edge_mutation():
    # Ensure the original list is mutated (in-place sorting)
    arr = [3, 2, 1]
    sorter(arr)

def test_sorter_edge_type_error():
    # Should raise TypeError if not passed a list
    with pytest.raises(TypeError):
        sorter("not a list")

def test_sorter_edge_non_numeric():
    # Should raise TypeError if list contains non-numeric values
    arr = [1, "a", 3]
    with pytest.raises(TypeError):
        # Bubble sort will fail on comparing int and str
        sorter(arr)

def test_sorter_edge_none_element():
    # Should raise TypeError if list contains None
    arr = [1, None, 3]
    with pytest.raises(TypeError):
        sorter(arr)
# codeflash_output is used to check that the output of the original code is the same as that of the optimized code.
#------------------------------------------------
from codeflash.bubble_sort import sorter

def test_sorter():
    sorter([-17869.0, 17868.5, 18269.0, 18268.5])

🔎 Concolic Coverage Tests and Runtime

To edit these changes git checkout codeflash/optimize-sorter-mejp2e6m and push.