[PAT]数列求和（20）

#include "stdio.h"
#include "malloc.h"
#include "math.h"
void calc(int num,int N,long *data);
int main()
{
    int N,num;
    long *result;
    scanf("%d",&num);
    scanf("%d",&N);
    result=(long *)malloc(N*sizeof(long));
    calc(num,N,result);
    return 0;
}
void calc(int num,int N,long *data)
{
    long i=0;
    long val=0;
    long dif;
    int j;
    if(num<=0||N<=0)
    {
        printf("0");
        return;
    }
    for(i=0;i<N||val>0;i++)
    {
        val=val+num*(N-i);
        dif=val%10;
        data[i]=dif;
        val=(val-dif)/10;
    }
    for(j=i-1;j>=0;j--)
    {
        printf("%ld",data[j]);
    }
}