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  1. """Professional Services Request Prioritization
  2.  
  3. Order: high -> medium -> low; within a priority, fewer estimated_hours first;
  4. full ties keep their original order.
  5. Works on plain Python 3 (no external libraries), so it runs on ideone as-is.
  6. """
  7.  
  8. # Lower number = handled earlier. A dict makes the rule easy to read and extend.
  9. PRIORITY_RANK = {"high": 0, "medium": 1, "low": 2}
  10.  
  11.  
  12. def _sort_key(request):
  13.     """Validate one request and return its (priority_rank, hours) sort key."""
  14.     # Required fields must exist
  15.     for field in ("id", "customer", "priority", "estimated_hours"):
  16.         if field not in request:
  17.             raise ValueError(f"Request is missing '{field}': {request}")
  18.  
  19.     # Normalise priority so "High" / " HIGH " still work
  20.     priority = str(request["priority"]).strip().lower()
  21.     if priority not in PRIORITY_RANK:
  22.         raise ValueError(
  23.             f"Unknown priority '{request['priority']}' in {request['id']}; "
  24.             f"expected one of {list(PRIORITY_RANK)}"
  25.         )
  26.  
  27.     # Hours must be a non-negative number (bool is an int in Python, so reject it)
  28.     hours = request["estimated_hours"]
  29.     if isinstance(hours, bool) or not isinstance(hours, (int, float)) or hours < 0:
  30.         raise ValueError(f"Invalid estimated_hours '{hours}' in {request['id']}")
  31.  
  32.     return PRIORITY_RANK[priority], hours
  33.  
  34.  
  35. def prioritize_requests(requests):
  36.     """Return a NEW list of requests in the order they should be handled.
  37.  
  38.     sorted() is stable: items with equal keys keep their original relative order,
  39.     which satisfies the "preserve original order on a full tie" rule for free.
  40.     The input list is not modified.
  41.     """
  42.     return sorted(requests, key=_sort_key)
  43.  
  44.  
  45. # ----------------------------- tests -----------------------------
  46.  
  47. def ids(requests):
  48.     return [r["id"] for r in requests]
  49.  
  50.  
  51. def make(req_id, priority, hours, customer="Acme"):
  52.     return {"id": req_id, "customer": customer, "priority": priority, "estimated_hours": hours}
  53.  
  54.  
  55. def test_sample_input():
  56.     sample = [
  57.         make("REQ-101", "medium", 3, "Alpha Ltd"),
  58.         make("REQ-102", "high", 5, "Beta Corp"),
  59.         make("REQ-103", "low", 2, "Alpha Ltd"),
  60.         make("REQ-104", "high", 4, "Gamma Inc"),
  61.     ]
  62.     assert ids(prioritize_requests(sample)) == ["REQ-104", "REQ-102", "REQ-101", "REQ-103"]
  63.  
  64.  
  65. def test_same_priority_orders_by_hours():
  66.     reqs = [make("A", "medium", 8), make("B", "medium", 1), make("C", "medium", 4)]
  67.     assert ids(prioritize_requests(reqs)) == ["B", "C", "A"]
  68.  
  69.  
  70. def test_tie_preserves_original_order():
  71.     # Same priority AND same hours -> must stay in input order (stability)
  72.     reqs = [make("FIRST", "high", 3), make("SECOND", "high", 3), make("THIRD", "high", 3)]
  73.     assert ids(prioritize_requests(reqs)) == ["FIRST", "SECOND", "THIRD"]
  74.  
  75.  
  76. def test_priority_beats_hours():
  77.     # A low-priority 1-hour job must not jump ahead of a high-priority 40-hour job
  78.     reqs = [make("LOW", "low", 1), make("HIGH", "high", 40)]
  79.     assert ids(prioritize_requests(reqs)) == ["HIGH", "LOW"]
  80.  
  81.  
  82. def test_empty_list():
  83.     assert prioritize_requests([]) == []
  84.  
  85.  
  86. def test_single_request_and_zero_hours():
  87.     reqs = [make("ONLY", "low", 0)]
  88.     assert ids(prioritize_requests(reqs)) == ["ONLY"]
  89.  
  90.  
  91. def test_priority_case_and_whitespace_insensitive():
  92.     reqs = [make("L", "LOW", 1), make("H", " High ", 9)]
  93.     assert ids(prioritize_requests(reqs)) == ["H", "L"]
  94.  
  95.  
  96. def test_float_hours():
  97.     reqs = [make("A", "high", 2.5), make("B", "high", 2.25)]
  98.     assert ids(prioritize_requests(reqs)) == ["B", "A"]
  99.  
  100.  
  101. def test_input_not_modified():
  102.     reqs = [make("A", "low", 1), make("B", "high", 1)]
  103.     snapshot = list(reqs)
  104.     prioritize_requests(reqs)
  105.     assert reqs == snapshot
  106.  
  107.  
  108. def test_invalid_data_raises():
  109.     bad_inputs = [
  110.         [make("X", "urgent", 2)],                      # unknown priority
  111.         [make("X", "high", -1)],                       # negative hours
  112.         [make("X", "high", "3")],                      # hours not a number
  113.         [make("X", "high", True)],                     # bool is not valid hours
  114.         [{"id": "X", "customer": "A", "priority": "high"}],   # missing field
  115.     ]
  116.     for bad in bad_inputs:
  117.         try:
  118.             prioritize_requests(bad)
  119.         except ValueError:
  120.             continue
  121.         raise AssertionError(f"Expected ValueError for {bad}")
  122.  
  123.  
  124. def run_tests():
  125.     tests = [v for k, v in globals().items() if k.startswith("test_") and callable(v)]
  126.     for test in tests:
  127.         test()
  128.         print(f"PASS  {test.__name__}")
  129.     print(f"\nAll {len(tests)} tests passed")
  130.  
  131.  
  132. if __name__ == "__main__":
  133.     sample_requests = [
  134.         make("REQ-101", "medium", 3, "Alpha Ltd"),
  135.         make("REQ-102", "high", 5, "Beta Corp"),
  136.         make("REQ-103", "low", 2, "Alpha Ltd"),
  137.         make("REQ-104", "high", 4, "Gamma Inc"),
  138.     ]
  139.     print("Handling order:")
  140.     for position, req in enumerate(prioritize_requests(sample_requests), start=1):
  141.         print(f"{position}. {req['id']}  {req['customer']:<10} "
  142.               f"{req['priority']:<6} {req['estimated_hours']}h")
  143.     print()
  144.     run_tests()
Success #stdin #stdout 0.07s 14152KB
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numbers = (1,2,3,3,2,4,5,4,6,6,7,8,8,9,0)
stdout
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Handling order:
1. REQ-104  Gamma Inc  high   4h
2. REQ-102  Beta Corp  high   5h
3. REQ-101  Alpha Ltd  medium 3h
4. REQ-103  Alpha Ltd  low    2h

PASS  test_sample_input
PASS  test_same_priority_orders_by_hours
PASS  test_tie_preserves_original_order
PASS  test_priority_beats_hours
PASS  test_empty_list
PASS  test_single_request_and_zero_hours
PASS  test_priority_case_and_whitespace_insensitive
PASS  test_float_hours
PASS  test_input_not_modified
PASS  test_invalid_data_raises

All 10 tests passed
https://ideone.com/4BRvOd
language:
Python 3 (python  3.12)
created:
11 hours ago
visibility:
public

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