HDU-1012u Calculate e

Problem Description

A simple mathematical formula for e is

where n is allowed to go to infinity. This can actually yield very accurate approximations of e using relatively small values of n.

 

Output

Output the approximations of e generated by the above formula for the values of n from 0 to 9. The beginning of your output should appear similar to that shown below.

 

Sample Output

n e - ----------- 0 1 1 2 2 2.5 3 2.666666667 4 2.708333333

 

解题报告：水题，无解题报告

#include<stdio.h>
double add(int n) {
    double s=1,x=1;
    for(int i=1;i<=n;++i) {
        x=1;
        for(int j=1;j<=i;++j)
        x*=j;
        s+=(1.0/x);
    }
    return s;
}
int main() {
    printf("n e\n- -----------\n0 1\n1 2\n2 2.5\n");
    for(int i=3;i<=9;++i) {
        double sum=add(i);
        printf("%d %.9lf\n",i,sum);
    }
    return 0;
}