<qiyuangong>268_Missing_Number_1.py
def missingNumber( nums):
    n = len(nums)
    return (n ** 2 + n) / 2 - sum(nums)
def sample_funcname ( var_0 ) :
    var_2 = len ( var_0 )
    return ( var_2 ** 2 + var_2 ) / 2 - sum ( var_0 )
