标准答案x1 = 1d = 3n = 100x100 = x1 + (n - 1) * ds = (x1 + x100) * n / 2print s问题所在x1 = 1d = 3n = 100s = (x1 + x1 + (n - 1) * d) * n / 2 #这样输入错在哪里print s 查看完整描述