PTA输出指定范围内的完数

#include <stdio.h>

int factorsum( int number );
void PrintPN( int m, int n );

int main()
{
    int i, m, n;

    scanf("%d %d", &m, &n);
    if ( factorsum(m) == m ) printf("%d is a perfect number\n", m);
    if ( factorsum(n) == n ) printf("%d is a perfect number\n", n);
    PrintPN(m, n);

    return 0;
}

int factorsum(int number)
{
    int sum=0;
    if(number==1)
        return 1;
    for(int i=1;i<number;i++)
    {
        if(number%i==0)
        {
            sum+=i;
        }
    }
    if(sum==number)
        return sum;
}

void PrintPN(int m,int n)
{
    int exist=0,isfactor=0;
    for(int j=m;j<=n;j++)
    {
        if(factorsum(j)==j)
        {
            exist=1;
            printf("%d =",j);
            if(j==1)
            {
                printf(" %d",j);
            }
            for(int k=1;k<j;k++) //此时j为完数
            {
                if(j%k==0)
                {
                    if(k==1)
                        printf(" 1");
                    else
                        printf(" + %d",k);
                }
            }
            printf("\n");
        }
    }
    if(exist==0)
    {
        printf("No perfect number");
    }
}