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