48 lines
1016 B
Python
48 lines
1016 B
Python
#!/usr/bin/env python3
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# Find the unique positive integer whose square has the form 1_2_3_4_5_6_7_8_9_0,
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# where each “_” is a single digit.
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from timeit import default_timer
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def main():
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start = default_timer()
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# Since the square of n has 19 digits, n must be at least 10^9.
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n = 1000000000
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found = 0
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while not found:
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# If the square on n ends with 10, n must be divisible by 10.
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n = n + 10
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p = n * n
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# A square divisible by 10 is also divisible by 100.
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if p % 100 != 0:
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continue
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# Check if the digits of the square correspond to the given pattern.
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i = 9
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p = p // 100
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while p > 0:
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if p % 10 != i:
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break
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p = p // 100
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i = i - 1
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if p == 0:
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found = 1
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end = default_timer()
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print('Project Euler, Problem 206')
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print(f'Answer: {n}')
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print(f'Elapsed time: {end - start:.9f} seconds')
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if __name__ == '__main__':
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main()
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