#includeint main(){int m,n;float sum;scanf("%d",&m);while(m-->0){sum=0;scanf("%d",&n);while(n){if(n%2==0)sum-=1.0/n; elsesum+=1.0/n;n--;}printf("%.2f\n",sum);}return 0;}
ifelse后面不加括号的话系统只默认紧跟的第一句属于它们。。需要多条语句要加括号!