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61f3119467
* f-string update rsa_cipher.py * f-string update rsa_key_generator.py * f-string update burrows_wheeler.py * f-string update non_recursive_segment_tree.py * f-string update red_black_tree.py * f-string update deque_doubly.py * f-string update climbing_stairs.py * f-string update iterating_through_submasks.py * f-string update knn_sklearn.py * f-string update 3n_plus_1.py * f-string update quadratic_equations_complex_numbers.py * f-string update nth_fibonacci_using_matrix_exponentiation.py * f-string update sherman_morrison.py * f-string update levenshtein_distance.py * fix lines that were too long
150 lines
2.7 KiB
Python
150 lines
2.7 KiB
Python
from __future__ import annotations
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def n31(a: int) -> tuple[list[int], int]:
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"""
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Returns the Collatz sequence and its length of any positive integer.
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>>> n31(4)
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([4, 2, 1], 3)
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"""
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if not isinstance(a, int):
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raise TypeError(f"Must be int, not {type(a).__name__}")
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if a < 1:
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raise ValueError(f"Given integer must be greater than 1, not {a}")
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path = [a]
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while a != 1:
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if a % 2 == 0:
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a = a // 2
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else:
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a = 3 * a + 1
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path += [a]
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return path, len(path)
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def test_n31():
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"""
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>>> test_n31()
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"""
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assert n31(4) == ([4, 2, 1], 3)
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assert n31(11) == ([11, 34, 17, 52, 26, 13, 40, 20, 10, 5, 16, 8, 4, 2, 1], 15)
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assert n31(31) == (
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[
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31,
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94,
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47,
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142,
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71,
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214,
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107,
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322,
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161,
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484,
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242,
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121,
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364,
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182,
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91,
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274,
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137,
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412,
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206,
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103,
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310,
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155,
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466,
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233,
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700,
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350,
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175,
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526,
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263,
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790,
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395,
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1186,
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593,
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1780,
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890,
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445,
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1336,
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668,
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334,
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167,
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502,
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251,
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754,
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377,
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1132,
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566,
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283,
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850,
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425,
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1276,
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638,
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319,
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958,
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479,
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1438,
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719,
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2158,
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1079,
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3238,
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1619,
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4858,
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2429,
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7288,
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3644,
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1822,
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911,
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2734,
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1367,
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4102,
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2051,
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6154,
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3077,
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9232,
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4616,
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2308,
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1154,
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577,
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1732,
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866,
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433,
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1300,
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650,
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325,
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976,
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488,
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244,
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122,
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61,
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184,
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92,
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46,
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23,
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70,
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35,
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106,
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53,
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160,
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80,
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40,
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20,
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10,
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5,
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16,
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8,
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4,
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2,
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1,
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],
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107,
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)
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if __name__ == "__main__":
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num = 4
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path, length = n31(num)
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print(f"The Collatz sequence of {num} took {length} steps. \nPath: {path}")
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