1 #include <stdio.h>
 2 
 3 int factorsum( int number );
 4 void PrintPN( int m, int n );
 5 
 6 int main()
 7 {
 8     int i, m, n;
 9 
10     scanf("%d %d", &m, &n);
11     if ( factorsum(m) == m ) printf("%d is a perfect number\n", m);
12     if ( factorsum(n) == n ) printf("
 
%d is a perfect number\n", n);
13     PrintPN(m, n);
14 
15     return 0;
16 }
17 
18 int factorsum(int number)
19 {
20     int sum=0;
21     if(number==1)
22         return 1;
23     for(int i=1;i<number;i++)
24     {
25         if(number%i==0)
26         {
27             sum+=i;
28         }
 
29     }
30     if(sum==number)
31         return sum;
32 }
33 
34 void PrintPN(int m,int n)
35 {
36     int exist=0,isfactor=0;
37     for(int j=m;j<=n;j++)
38     {
39         if(factorsum(j)==j)
40         {
41             exist=1;
42             printf("%d =",j);
43             if(j==1
 
)
44             {
45                 printf(" %d",j);
46             }
47             for(int k=1;k<j;k++) //此時j為完數
48             {
49                 if(j%k==0)
50                 {
51                     if(k==1)
52                         printf(" 1");
53                     else
54                         printf(" + %d",k);
55                 }
56             }
57             printf("\n");
58         }
59     }
60     if(exist==0)
61     {
62         printf("No perfect number");
63     }
64 }