Problem Statement |
| | A lucky number is a number whose decimal representation contains only the digits 4 and 7. An almost lucky number is a number that is divisible by a lucky number. For example, 14, 36 and 747 are almost lucky, but 2 and 17 are not. Note that a number can be both lucky and almost lucky at the same time (for example, 747).
You are given longs a and b. Return the number of almost lucky numbers between a and b, inclusive. |
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Definition |
| | | Class: | TheAlmostLuckyNumbers | | Method: | count | | Parameters: | long, long | | Returns: | long | | Method signature: | long count(long a, long b) | | (be sure your method is public) |
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Constraints |
| - | a will be between 1 and 10,000,000,000, inclusive. |
| - | b will be between a and 10,000,000,000, inclusive. |
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Examples |
| 0) | |
| | | Returns: 3 | | There are three almost lucky numbers less than or equal to ten - 4, 7 and 8. |
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| 1) | |
| | | Returns: 1 | | 14 is an almost lucky number. |
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| 2) | |
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| 3) | |
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