51 lines
804 B
Markdown
51 lines
804 B
Markdown
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---
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title: 最大公约数gcd
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updated: 2022-01-14 01:51:50Z
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created: 2022-01-08 13:18:07Z
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tags:
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- mcu
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- pll
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- 代码块
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---
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# 含义
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great common divisor, gcd
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能够整除多个整数的最大正整数
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# 算法
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## 辗转相除法
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$gcd(a,0)=a$
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$gcd(a,b)=gcd(b,a mod b)$
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如果参数都大于0，那么可以简写成
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$gcd(a,a)=a$
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$gcd(a,b)=gcd(a-b,a), if \space a>b$
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$gcd(a,b)=gcd(a,b-a), if \space a<b$
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### 代码
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```c
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int gcd(int a, int b)
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{
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if(b)
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{
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while((a %= b) && (b %= a));
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return a + b
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}
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}
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```
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```c
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// greatest common denominator - euclid algo w/o recursion
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uint32_t gcd_iter(uint32_t u, uint32_t v)
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{
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uint32_t t;
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while (v) {
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t = u;
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u = v;
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v = t % v;
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}
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return u ;
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}
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```
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#mcu
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#pll
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#代码块
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