1-1-2+1-3-1-4…+(-)1-n=？

转化分母(1)1/11/1(1)(2)1-1/21/2(2)(3)1-1/2+1/31/2+1/3(2,3)(4)1-1/2+1/3-1/41/3+1/4(3,4)(5)1/3+1/4+1/5(3,4,5)(6)1/4+1/5+1/6(4,5,6)(7)1/4+1/5+1/6+1/7(4,5,6,7)(8)1/5+1/6+1/7+1/8(5,6,7,8)函数f(n){让res=0;for(leti=n;i>=Math.floor(n/2)+1;i--){res+=(1/i);}返回资源；}