public class Sum {
public static void main(String[] args) {
double a = 1.0;
// 接收最后结果
double sum = 0.0;
// 循环 i的值从1-100
for (int i = 1; i <= 100; i++) {
// 观察算式,分母是偶数时,分数为负
if(i%2 == 0)
sum += -(a/i);
else
sum += (a/i);
}
System.out.println(sum);
}
}