{ "data": { "question": { "questionId": "2457", "questionFrontendId": "2376", "boundTopicId": null, "title": "Count Special Integers", "titleSlug": "count-special-integers", "content": "

We call a positive integer special if all of its digits are distinct.

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Given a positive integer n, return the number of special integers that belong to the interval [1, n].

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Example 1:

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\nInput: n = 20\nOutput: 19\nExplanation: All the integers from 1 to 20, except 11, are special. Thus, there are 19 special integers.\n
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Example 2:

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\nInput: n = 5\nOutput: 5\nExplanation: All the integers from 1 to 5 are special.\n
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Example 3:

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\nInput: n = 135\nOutput: 110\nExplanation: There are 110 integers from 1 to 135 that are special.\nSome of the integers that are not special are: 22, 114, and 131.
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Constraints:

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