sigma 求和

d.txt

5
8

main.c

#include<stdio.h>

void main(){
    int k,x,p=1,sum=0,ans;
    float sig=0;
    FILE *fpr=fopen("d.txt","r");
    fscanf(fpr,"%d\n %d",&x,&k);
    for (int i=1;i<=k;i++){
        sum=i;
        for(int t=sum-1;t>0;t--){
            sum=sum*t;
        }
        sig=sig+pow (x,i)/sum;
    }
    ans=(int)sig;
    printf("%d\n",ans);
}