欧拉函数的递推形式

 1 #include <stdio.h>
 2 int main()
 3 {
 4 int n;
 5 scanf("%d",&n);
 6 int* a=new int[n+1];
 7 for (int i = 1; i < n; i++) a[i] = i;
 8 for (int i = 2; i < n; i += 2) a[i] /= 2;
 9 for (int i = 3; i < n; i += 2) 
10 if(a[i] == i) 
11 {
12 for (int j = i; j < n; j += i)
13 a[j] = a[j] / i * (i - 1);
14 }
15 for (int i=1;i<n;i++)
16 printf("%d ",a[i]);
17 return 0;
18