Question

1.编写程序：求数列：1/1-1/2+1/3-1/4+ ???+1/90-1/100之和

....

Answer 1

package test01;
//求数列：1/1-1/2+1/3-1/4+ ???+1/90-1/100之和
public class math01 {
public double getAnswer(){

double b = 0.00;
for(double i = 1;i<=100;i++){

if(i%2==0){
b-=1/i;
}else{
b+=1/i;
}
}

return b;
}
public static void main(String[] args) {
math01 m = new math01();
System.out.println(m.getAnswer());
}
}

用java写的

Answer 2

核心是
main()
{
int i,t=0,m=0;s=0;
for(i=1;i<=100;i++)
t+=1/i;
for(i=1;i<=100;i+2)
m+=1/i;
s=t-m;
}

Answer 3

不知道你用什么语言，我就用perl写了，算法都是共通的

$sum = 0;
for($i=1,$i<=100,$i++)
{
$f=(-1)**($i-1);
$sum += 1 / $i * $f;
}

print $sum;

Answer 4

function test(n)
{
f=100000;
sum=0;

for(i=1;i<n;i+=2)
{
sum+=f*1/i;
f*=-1;
}
sum=sum/100000;
return sum;
}

test(100)结果为:

0.7803986631477524