题目：sum函数的功能为计算1+2+3+……+n的累加和，请填写程序 所缺内容。 def sum(n): #**********SPACE********** a = [x for x in range(1,n)] #**********SPACE********** b = (a[0] + a[-1]) * (len(a)//2) if len(a) % 2 != 0: #**********SPACE********** b += a[len(a) % 2] return b def main(): n=int(input("请输入整型数值n：")) print(sum(n)) if __name__ == '__main__': main()

def sum(n):
a = [x for x in range(1, n + 1)]
b = (a[0] + a[-1]) * (len(a) // 2)
if len(a) % 2 != 0:
b += a[len(a) // 2]
return b

def main():
n = int(input("请输入整型数值n："))
print(sum(n))

if __name__ == '__main__':
main()