2019-11-02 12:07:41 +08:00
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# 43. 从 1 到 n 整数中 1 出现的次数
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[NowCoder](https://www.nowcoder.com/practice/bd7f978302044eee894445e244c7eee6?tpId=13&tqId=11184&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
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## 解题思路
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```java
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public int NumberOf1Between1AndN_Solution(int n) {
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int cnt = 0;
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for (int m = 1; m <= n; m *= 10) {
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int a = n / m, b = n % m;
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cnt += (a + 8) / 10 * m + (a % 10 == 1 ? b + 1 : 0);
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}
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return cnt;
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}
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```
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2020-11-18 03:00:45 +08:00
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> [Leetcode : 233. Number of Digit One](https://leetcode.com/problems/number-of-digit-one/discuss/64381/4+-lines-O(log-n)-C++JavaPython)
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