48 lines
1.3 KiB
Markdown
48 lines
1.3 KiB
Markdown
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## Briefcase Lock
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A briefcase has a 4-digit **rolling-lock**. Each digit is a number from `0-9` that can be rolled either forwards or backwards.
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Create a function that returns the smallest number of turns it takes to transform the lock from the current combination to the target combination. One turn is equivalent to rolling a number forwards or backwards by one.
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To illustrate:
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- **current-lock**: 4089
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- **target-lock**: 5672
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What is the minimum number of turns it takes to transform `4089` to `5672`?
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```
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4 ➞ 5
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4 ➞ 5 // Forward Turns: 1 <- Min
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4 ➞ 3 ➞ 2 ➞ 1 ➞ 0 ➞ 9 ➞ 8 ➞ 7 ➞ 6 ➞ 5 // Backward Turns: 9
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0 ➞ 6
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0 ➞ 1 ➞ 2 ➞ 3 ➞ 4 ➞ 5 ➞ 6 // Forward Turns: 6
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0 ➞ 9 ➞ 8 ➞ 7 ➞ 6 // Backward Turns: 4 <- Min
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8 ➞ 7
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8 ➞ 9 ➞ 0 ➞ 1 ➞ 2 ➞ 3 ➞ 4 ➞ 5 ➞ 6 ➞ 7 // Forward Turns: 9
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8 ➞ 7 // Backward Turns: 1 <- Min
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9 ➞ 2
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9 ➞ 0 ➞ 1 ➞ 2 // Forward Turns: 3 <- Min
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9 ➞ 8 ➞ 7 ➞ 6 ➞ 5 ➞ 4 ➞ 3 ➞ 2 // Backward Turns: 7
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```
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It takes `1 + 4 + 1 + 3 = 9` minimum turns to change the lock from `4089` to `5672`.
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### Example
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```text
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MinTurns("4089", "5672") ➞ 9
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MinTurns("1111", "1100") ➞ 2
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MinTurns("2391", "4984") ➞ 10
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```
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### Notes
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- Both locks are in string format.
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- A `9` rolls forward to `0`, and a `0` rolls backwards to a `9`.
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