RoseCode

Problem #341

Unreachable numbers
 Public ★(x12) 07/15/16 by Philippe_57721 7xp Programming 66.7%

Using four numbers 4 and the 4 operations +, -, *, / we can build all numbers up to 9.
• 1 = ((4 + 4) - 4) / 4
• 2 = (4 / (4 + 4)) * 4
• 3 = ((4 + 4) + 4) / 4
• 4 = ((4 - 4) * 4) + 4
• 5 = ((4 * 4) + 4) / 4
• 6 = ((4 + 4) / 4) + 4
• 7 = (4 - (4 / 4)) + 4
• 8 = ((4 + 4) + 4) - 4
• 9 = ((4 / 4) + 4) + 4
• 12 = (4 - (4 / 4)) * 4
$\Rightarrow$ 10 is the first not reachable

With four numbers 5
• 1 = ((5 + 5) - 5) / 5
• 2 = (5 / 5) + (5 / 5)
• 3 = ((5 + 5) + 5) / 5
• 4 = ((5 * 5) - 5) / 5
• 5 = ((5 - 5) * 5) + 5
• 6 = ((5 * 5) + 5) / 5
• 7 = ((5 + 5) / 5) + 5
• 9 = (5 - (5 / 5)) + 5
$\Rightarrow$ 8 is the first not reachable

What are the first unreachable numbers when we use eight 4 and eight 5?

Answer format: $u_4,u_5$

Example: 10,8

[My timing: 40 sec]

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