| {"id": "t2_001", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "two_sum", "buggy_code": "def two_sum(nums, target):\n seen = {}\n for i, num in enumerate(nums):\n complement = target - num\n if complement in seen:\n return [seen[complement], i]\n seen[num] = num\n return []", "original_code": "def two_sum(nums, target):\n seen = {}\n for i, num in enumerate(nums):\n complement = target - num\n if complement in seen:\n return [seen[complement], i]\n seen[num] = i\n return []", "initial_error": "AssertionError: two_sum([2,7,11,15], 9) expected [0,1], got [2,1]", "bug_location": {"function": "two_sum", "line_start": 7}, "test_cases": [{"input": [[2, 7, 11, 15], 9], "expected_output": [0, 1]}, {"input": [[3, 2, 4], 6], "expected_output": [1, 2]}, {"input": [[3, 3], 6], "expected_output": [0, 1]}]} |
| {"id": "t2_002", "difficulty": 2, "bug_type": "missing_base_case", "function_name": "fibonacci", "buggy_code": "def fibonacci(n):\n if n == 0:\n return 0\n return fibonacci(n - 1) + fibonacci(n - 2)", "original_code": "def fibonacci(n):\n if n == 0:\n return 0\n if n == 1:\n return 1\n return fibonacci(n - 1) + fibonacci(n - 2)", "initial_error": "RecursionError: maximum recursion depth exceeded", "bug_location": {"function": "fibonacci", "line_start": 4}, "test_cases": [{"input": [0], "expected_output": 0}, {"input": [1], "expected_output": 1}, {"input": [5], "expected_output": 5}, {"input": [7], "expected_output": 13}]} |
| {"id": "t2_003", "difficulty": 2, "bug_type": "wrong_accumulator", "function_name": "flatten", "buggy_code": "def flatten(lst):\n result = []\n for item in lst:\n if isinstance(item, list):\n result.append(flatten(item))\n else:\n result.append(item)\n return result", "original_code": "def flatten(lst):\n result = []\n for item in lst:\n if isinstance(item, list):\n result.extend(flatten(item))\n else:\n result.append(item)\n return result", "initial_error": "AssertionError: flatten([[1,[2]],3]) expected [1,2,3], got [1,[2],3]", "bug_location": {"function": "flatten", "line_start": 5}, "test_cases": [{"input": [[[1, [2]], 3]], "expected_output": [1, 2, 3]}, {"input": [[1, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[[1, 2], [3, [4, 5]]]], "expected_output": [1, 2, 3, 4, 5]}]} |
| {"id": "t2_004", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "find_first_positive", "buggy_code": "def find_first_positive(nums):\n i = 0\n while i < len(nums) - 1:\n if nums[i] > 0:\n return nums[i]\n i += 1\n return -1", "original_code": "def find_first_positive(nums):\n i = 0\n while i < len(nums):\n if nums[i] > 0:\n return nums[i]\n i += 1\n return -1", "initial_error": "AssertionError: expected 5, got -1", "bug_location": {"function": "find_first_positive", "line_start": 3}, "test_cases": [{"input": [[-1, -2, 5]], "expected_output": 5}, {"input": [[1, 2, 3]], "expected_output": 1}, {"input": [[-1]], "expected_output": -1}, {"input": [[-5, -3, -1, 10]], "expected_output": 10}]} |
| {"id": "t2_005", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "binary_search_insert", "buggy_code": "def binary_search_insert(arr, target):\n left, right = 0, len(arr) - 1\n while left < right:\n mid = (left + right) // 2\n if arr[mid] < target:\n left = mid + 1\n else:\n right = mid\n return left", "original_code": "def binary_search_insert(arr, target):\n left, right = 0, len(arr)\n while left < right:\n mid = (left + right) // 2\n if arr[mid] < target:\n left = mid + 1\n else:\n right = mid\n return left", "initial_error": "AssertionError: expected 3, got 2", "bug_location": {"function": "binary_search_insert", "line_start": 2}, "test_cases": [{"input": [[1, 3, 5], 6], "expected_output": 3}, {"input": [[1, 3, 5], 4], "expected_output": 2}, {"input": [[1, 3, 5], 0], "expected_output": 0}, {"input": [[], 1], "expected_output": 0}]} |
| {"id": "t2_006", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "countdown_to_zero", "buggy_code": "def countdown_to_zero(n):\n res = []\n while n > 0:\n res.append(n)\n n -= 1\n return res", "original_code": "def countdown_to_zero(n):\n res = []\n while n >= 0:\n res.append(n)\n n -= 1\n return res", "initial_error": "AssertionError: expected [3, 2, 1, 0], got [3, 2, 1]", "bug_location": {"function": "countdown_to_zero", "line_start": 3}, "test_cases": [{"input": [3], "expected_output": [3, 2, 1, 0]}, {"input": [0], "expected_output": [0]}, {"input": [1], "expected_output": [1, 0]}, {"input": [-1], "expected_output": []}]} |
| {"id": "t2_007", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "collect_until_negative", "buggy_code": "def collect_until_negative(nums):\n res = []\n i = 0\n while i <= len(nums) and nums[i] >= 0:\n res.append(nums[i])\n i += 1\n return res", "original_code": "def collect_until_negative(nums):\n res = []\n i = 0\n while i < len(nums) and nums[i] >= 0:\n res.append(nums[i])\n i += 1\n return res", "initial_error": "IndexError: list index out of range", "bug_location": {"function": "collect_until_negative", "line_start": 4}, "test_cases": [{"input": [[1, 2, -1, 3]], "expected_output": [1, 2]}, {"input": [[1, 2, 3]], "expected_output": [1, 2, 3]}, {"input": [[-1]], "expected_output": []}, {"input": [[]], "expected_output": []}]} |
| {"id": "t2_008", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "skip_spaces", "buggy_code": "def skip_spaces(s):\n i = 0\n while s[i] == ' ':\n i += 1\n return s[i:]", "original_code": "def skip_spaces(s):\n i = 0\n while i < len(s) and s[i] == ' ':\n i += 1\n return s[i:]", "initial_error": "IndexError: string index out of range", "bug_location": {"function": "skip_spaces", "line_start": 3}, "test_cases": [{"input": [" hello"], "expected_output": "hello"}, {"input": [" "], "expected_output": ""}, {"input": ["world"], "expected_output": "world"}, {"input": [""], "expected_output": ""}]} |
| {"id": "t2_009", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "find_last_even", "buggy_code": "def find_last_even(nums):\n i = len(nums) - 1\n while i > 0:\n if nums[i] % 2 == 0:\n return nums[i]\n i -= 1\n return -1", "original_code": "def find_last_even(nums):\n i = len(nums) - 1\n while i >= 0:\n if nums[i] % 2 == 0:\n return nums[i]\n i -= 1\n return -1", "initial_error": "AssertionError: expected 2, got -1", "bug_location": {"function": "find_last_even", "line_start": 3}, "test_cases": [{"input": [[2, 3, 5]], "expected_output": 2}, {"input": [[1, 3, 4]], "expected_output": 4}, {"input": [[1, 3, 5]], "expected_output": -1}, {"input": [[6]], "expected_output": 6}]} |
| {"id": "t2_010", "difficulty": 2, "bug_type": "wrong_loop_termination", "function_name": "get_chunks", "buggy_code": "def get_chunks(lst, size):\n chunks = []\n i = 0\n while i < len(lst) - size:\n chunks.append(lst[i:i+size])\n i += size\n return chunks", "original_code": "def get_chunks(lst, size):\n chunks = []\n i = 0\n while i < len(lst):\n chunks.append(lst[i:i+size])\n i += size\n return chunks", "initial_error": "AssertionError: expected [[1,2],[3]], got [[1,2]]", "bug_location": {"function": "get_chunks", "line_start": 4}, "test_cases": [{"input": [[1, 2, 3], 2], "expected_output": [[1, 2], [3]]}, {"input": [[1, 2], 2], "expected_output": [[1, 2]]}, {"input": [[1, 2, 3, 4], 2], "expected_output": [[1, 2], [3, 4]]}, {"input": [[], 2], "expected_output": []}]} |
| {"id": "t2_011", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "sum_even_numbers", "buggy_code": "def sum_even_numbers(nums):\n total = 1\n for n in nums:\n if n % 2 == 0:\n total += n\n return total", "original_code": "def sum_even_numbers(nums):\n total = 0\n for n in nums:\n if n % 2 == 0:\n total += n\n return total", "initial_error": "AssertionError: expected 6, got 7", "bug_location": {"function": "sum_even_numbers", "line_start": 2}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": 6}, {"input": [[1, 3, 5]], "expected_output": 0}, {"input": [[2, 2]], "expected_output": 4}, {"input": [[]], "expected_output": 0}]} |
| {"id": "t2_012", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "multiply_all", "buggy_code": "def multiply_all(nums):\n total = 0\n for n in nums:\n total *= n\n return total", "original_code": "def multiply_all(nums):\n total = 1\n for n in nums:\n total *= n\n return total", "initial_error": "AssertionError: expected 24, got 0", "bug_location": {"function": "multiply_all", "line_start": 2}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": 24}, {"input": [[5]], "expected_output": 5}, {"input": [[1, -1]], "expected_output": -1}, {"input": [[0, 5]], "expected_output": 0}]} |
| {"id": "t2_013", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "concatenate_strings", "buggy_code": "def concatenate_strings(strs):\n res = strs[0]\n for s in strs:\n res += s\n return res", "original_code": "def concatenate_strings(strs):\n res = ''\n for s in strs:\n res += s\n return res", "initial_error": "AssertionError: expected 'abc', got 'aabc'", "bug_location": {"function": "concatenate_strings", "line_start": 2}, "test_cases": [{"input": [["a", "b", "c"]], "expected_output": "abc"}, {"input": [["hello", "world"]], "expected_output": "helloworld"}, {"input": [["a"]], "expected_output": "a"}, {"input": [["x", "y"]], "expected_output": "xy"}]} |
| {"id": "t2_014", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "max_profit", "buggy_code": "def max_profit(prices):\n min_price = 0\n max_prof = 0\n for price in prices:\n min_price = min(min_price, price)\n max_prof = max(max_prof, price - min_price)\n return max_prof", "original_code": "def max_profit(prices):\n min_price = float('inf')\n max_prof = 0\n for price in prices:\n min_price = min(min_price, price)\n max_prof = max(max_prof, price - min_price)\n return max_prof", "initial_error": "AssertionError: expected 5, got 6", "bug_location": {"function": "max_profit", "line_start": 2}, "test_cases": [{"input": [[7, 1, 5, 3, 6, 4]], "expected_output": 5}, {"input": [[7, 6, 4, 3, 1]], "expected_output": 0}, {"input": [[1, 2]], "expected_output": 1}, {"input": [[2, 4, 1]], "expected_output": 2}]} |
| {"id": "t2_015", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "find_longest_word", "buggy_code": "def find_longest_word(words):\n longest = words[0]\n for word in words:\n if len(word) > len(longest):\n longest = longest\n return longest", "original_code": "def find_longest_word(words):\n longest = ''\n for word in words:\n if len(word) > len(longest):\n longest = word\n return longest", "initial_error": "AssertionError: expected 'banana', got 'apple'", "bug_location": {"function": "find_longest_word", "line_start": 5}, "test_cases": [{"input": [["apple", "banana", "kiwi"]], "expected_output": "banana"}, {"input": [["a", "ab", "abc"]], "expected_output": "abc"}, {"input": [["dog"]], "expected_output": "dog"}, {"input": [["x", "yz"]], "expected_output": "yz"}]} |
| {"id": "t2_016", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "running_sum", "buggy_code": "def running_sum(nums):\n res = []\n current = nums[0]\n for n in nums:\n current += n\n res.append(current)\n return res", "original_code": "def running_sum(nums):\n res = []\n current = 0\n for n in nums:\n current += n\n res.append(current)\n return res", "initial_error": "AssertionError: expected [1, 3, 6], got [2, 4, 7]", "bug_location": {"function": "running_sum", "line_start": 3}, "test_cases": [{"input": [[1, 2, 3]], "expected_output": [1, 3, 6]}, {"input": [[1, 1, 1]], "expected_output": [1, 2, 3]}, {"input": [[5]], "expected_output": [5]}, {"input": [[0, 0, 0]], "expected_output": [0, 0, 0]}]} |
| {"id": "t2_017", "difficulty": 2, "bug_type": "incorrect_accumulation", "function_name": "count_negatives", "buggy_code": "def count_negatives(nums):\n count = -1\n for n in nums:\n if n < 0:\n count += 1\n return count", "original_code": "def count_negatives(nums):\n count = 0\n for n in nums:\n if n < 0:\n count += 1\n return count", "initial_error": "AssertionError: expected 2, got 1", "bug_location": {"function": "count_negatives", "line_start": 2}, "test_cases": [{"input": [[1, -1, 2, -2]], "expected_output": 2}, {"input": [[1, 2, 3]], "expected_output": 0}, {"input": [[-1, -2, -3]], "expected_output": 3}, {"input": [[]], "expected_output": 0}]} |
| {"id": "t2_018", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "classify_number", "buggy_code": "def classify_number(n):\n if n > 0:\n return 'positive'\n elif n < 0:\n return 'negative'\n elif n == 0:\n return 'negative'", "original_code": "def classify_number(n):\n if n > 0:\n return 'positive'\n elif n < 0:\n return 'negative'\n else:\n return 'zero'", "initial_error": "AssertionError: expected 'zero', got 'negative'", "bug_location": {"function": "classify_number", "line_start": 6}, "test_cases": [{"input": [5], "expected_output": "positive"}, {"input": [-3], "expected_output": "negative"}, {"input": [0], "expected_output": "zero"}, {"input": [1], "expected_output": "positive"}]} |
| {"id": "t2_019", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "get_discount", "buggy_code": "def get_discount(price):\n if price > 100:\n return 20\n if price > 50:\n return 50\n return 0", "original_code": "def get_discount(price):\n if price > 100:\n return 20\n elif price > 50:\n return 10\n return 0", "initial_error": "AssertionError: expected 10, got 50", "bug_location": {"function": "get_discount", "line_start": 5}, "test_cases": [{"input": [150], "expected_output": 20}, {"input": [75], "expected_output": 10}, {"input": [50], "expected_output": 0}, {"input": [20], "expected_output": 0}]} |
| {"id": "t2_020", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "fizz_buzz", "buggy_code": "def fizz_buzz(n):\n if n % 3 == 0:\n return 'Fizz'\n if n % 5 == 0:\n return 'Buzz'\n if n % 15 == 0:\n return 'FizzBuzz'\n return str(n)", "original_code": "def fizz_buzz(n):\n if n % 15 == 0:\n return 'FizzBuzz'\n if n % 3 == 0:\n return 'Fizz'\n if n % 5 == 0:\n return 'Buzz'\n return str(n)", "initial_error": "AssertionError: expected 'FizzBuzz', got 'Fizz'", "bug_location": {"function": "fizz_buzz", "line_start": 2}, "test_cases": [{"input": [3], "expected_output": "Fizz"}, {"input": [5], "expected_output": "Buzz"}, {"input": [15], "expected_output": "FizzBuzz"}, {"input": [2], "expected_output": "2"}]} |
| {"id": "t2_021", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "is_leap_year", "buggy_code": "def is_leap_year(year):\n if year % 4 == 0:\n if year % 100 == 0:\n if year % 400 == 0:\n return False\n return True\n return True\n return False", "original_code": "def is_leap_year(year):\n if year % 4 == 0:\n if year % 100 == 0:\n if year % 400 == 0:\n return True\n return False\n return True\n return False", "initial_error": "AssertionError: expected False, got True", "bug_location": {"function": "is_leap_year", "line_start": 5}, "test_cases": [{"input": [2000], "expected_output": true}, {"input": [1900], "expected_output": false}, {"input": [2004], "expected_output": true}, {"input": [2001], "expected_output": false}]} |
| {"id": "t2_022", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "grade_score", "buggy_code": "def grade_score(score):\n if score >= 90:\n return 'A'\n elif score >= 80:\n return 'B'\n elif score > 70:\n return 'C'\n else:\n return 'F'", "original_code": "def grade_score(score):\n if score >= 90:\n return 'A'\n elif score >= 80:\n return 'B'\n elif score >= 70:\n return 'C'\n else:\n return 'F'", "initial_error": "AssertionError: expected 'C', got 'F'", "bug_location": {"function": "grade_score", "line_start": 6}, "test_cases": [{"input": [95], "expected_output": "A"}, {"input": [80], "expected_output": "B"}, {"input": [70], "expected_output": "C"}, {"input": [60], "expected_output": "F"}]} |
| {"id": "t2_023", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "can_drink_alcohol", "buggy_code": "def can_drink_alcohol(age, country):\n if country == 'US':\n if age > 21:\n return True\n return False\n return age >= 18", "original_code": "def can_drink_alcohol(age, country):\n if country == 'US':\n if age >= 21:\n return True\n return False\n return age >= 18", "initial_error": "AssertionError: expected True, got False", "bug_location": {"function": "can_drink_alcohol", "line_start": 3}, "test_cases": [{"input": [21, "US"], "expected_output": true}, {"input": [20, "US"], "expected_output": false}, {"input": [18, "UK"], "expected_output": true}, {"input": [17, "UK"], "expected_output": false}]} |
| {"id": "t2_024", "difficulty": 2, "bug_type": "wrong_conditional_branch", "function_name": "get_quadrant", "buggy_code": "def get_quadrant(x, y):\n if x > 0 and y > 0:\n return 1\n elif x < 0 and y > 0:\n return 2\n elif x > 0 and y < 0:\n return 3\n elif x < 0 and y < 0:\n return 4\n return 0", "original_code": "def get_quadrant(x, y):\n if x > 0 and y > 0:\n return 1\n elif x < 0 and y > 0:\n return 2\n elif x < 0 and y < 0:\n return 3\n elif x > 0 and y < 0:\n return 4\n return 0", "initial_error": "AssertionError: expected 4, got 3", "bug_location": {"function": "get_quadrant", "line_start": 6}, "test_cases": [{"input": [1, 1], "expected_output": 1}, {"input": [-1, 1], "expected_output": 2}, {"input": [-1, -1], "expected_output": 3}, {"input": [1, -1], "expected_output": 4}]} |
| {"id": "t2_025", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "merge_arrays", "buggy_code": "def merge_arrays(a, b):\n res = a + b\n res.sort()\n return a", "original_code": "def merge_arrays(a, b):\n res = a + b\n res.sort()\n return res", "initial_error": "AssertionError: expected [1, 2, 3, 4], got [1, 3]", "bug_location": {"function": "merge_arrays", "line_start": 4}, "test_cases": [{"input": [[1, 3], [2, 4]], "expected_output": [1, 2, 3, 4]}, {"input": [[], [1]], "expected_output": [1]}, {"input": [[2], [1]], "expected_output": [1, 2]}, {"input": [[], []], "expected_output": []}]} |
| {"id": "t2_026", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "find_min_max", "buggy_code": "def find_min_max(nums):\n if not nums:\n return None\n mn = min(nums)\n mx = max(nums)\n return [mn, mn]", "original_code": "def find_min_max(nums):\n if not nums:\n return None\n mn = min(nums)\n mx = max(nums)\n return [mn, mx]", "initial_error": "AssertionError: expected (1, 5), got (1, 1)", "bug_location": {"function": "find_min_max", "line_start": 6}, "test_cases": [{"input": [[1, 2, 5]], "expected_output": [1, 5]}, {"input": [[3, 3]], "expected_output": [3, 3]}, {"input": [[-1, 0, 1]], "expected_output": [-1, 1]}, {"input": [[]], "expected_output": null}]} |
| {"id": "t2_027", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "remove_evens", "buggy_code": "def remove_evens(nums):\n res = []\n for n in nums:\n if n % 2 != 0:\n res.append(n)\n return nums", "original_code": "def remove_evens(nums):\n res = []\n for n in nums:\n if n % 2 != 0:\n res.append(n)\n return res", "initial_error": "AssertionError: expected [1, 3], got [1, 2, 3]", "bug_location": {"function": "remove_evens", "line_start": 6}, "test_cases": [{"input": [[1, 2, 3]], "expected_output": [1, 3]}, {"input": [[2, 4]], "expected_output": []}, {"input": [[1, 3]], "expected_output": [1, 3]}, {"input": [[]], "expected_output": []}]} |
| {"id": "t2_028", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "duplicate_list", "buggy_code": "def duplicate_list(lst):\n res = lst[:]\n res.extend(lst)\n return lst", "original_code": "def duplicate_list(lst):\n res = lst[:]\n res.extend(lst)\n return res", "initial_error": "AssertionError: expected [1, 1], got [1]", "bug_location": {"function": "duplicate_list", "line_start": 4}, "test_cases": [{"input": [[1]], "expected_output": [1, 1]}, {"input": [[1, 2]], "expected_output": [1, 2, 1, 2]}, {"input": [[]], "expected_output": []}, {"input": [[0]], "expected_output": [0, 0]}]} |
| {"id": "t2_029", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "swap_halves", "buggy_code": "def swap_halves(lst):\n mid = len(lst) // 2\n left = lst[:mid]\n right = lst[mid:]\n return left + left", "original_code": "def swap_halves(lst):\n mid = len(lst) // 2\n left = lst[:mid]\n right = lst[mid:]\n return right + left", "initial_error": "AssertionError: expected [3, 4, 1, 2], got [1, 2, 1, 2]", "bug_location": {"function": "swap_halves", "line_start": 5}, "test_cases": [{"input": [[1, 2, 3, 4]], "expected_output": [3, 4, 1, 2]}, {"input": [[1, 2, 3]], "expected_output": [2, 3, 1]}, {"input": [[1]], "expected_output": [1]}, {"input": [[]], "expected_output": []}]} |
| {"id": "t2_030", "difficulty": 2, "bug_type": "wrong_variable", "function_name": "get_initials", "buggy_code": "def get_initials(name):\n words = name.split()\n initials = [w[0].upper() for w in words]\n return ''.join(words)", "original_code": "def get_initials(name):\n words = name.split()\n initials = [w[0].upper() for w in words]\n return ''.join(initials)", "initial_error": "AssertionError: expected 'JD', got 'JohnDoe'", "bug_location": {"function": "get_initials", "line_start": 4}, "test_cases": [{"input": ["John Doe"], "expected_output": "JD"}, {"input": ["Alice"], "expected_output": "A"}, {"input": ["bob smith junior"], "expected_output": "BSJ"}, {"input": [""], "expected_output": ""}]} |
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