数位型

状态：f[pos][mask][bound]

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灵神 @灵茶山艾府 的 [数位dp] 相关题目：

• 面试题17.06 https://leetcode.cn/problems/number-of-2s-in-range-lcci/
• 233 https://leetcode.cn/problems/number-of-digit-one/
• 600 https://leetcode.cn/problems/non-negative-integers-without-consecutive-ones/
• 902 https://leetcode.cn/problems/numbers-at-most-n-given-digit-set/
• 1012 https://leetcode.cn/problems/numbers-with-repeated-digits/
• 1067 https://leetcode.cn/problems/digit-count-in-range/
• 1397 https://leetcode.cn/problems/find-all-good-strings/
• 2376 https://leetcode.cn/problems/count-special-integers/