溢出错误：无法将浮点无穷大转换为 integer python3？

Question

我正在尝试编写一个程序来解决这种模式并获得第 n 个位置的值（ n 从 1 变化到 10^5 ）

1,2,7,20,61,182...参考

我能够写一个 function 来做到这一点。 但不断获得

OverflowError: cannot convert float infinity to integer

py3中出现较大n输入的错误。 但它在py2中运行良好。

   def getPattern(n):
    total = 2
    tmptotal = 1
    count = 2

    if(n == 1 or n == 2):
        print(n)
    else:
        for i in range(2, n):
            if(count == 2):
                total = (total + (total/2))*2 + 1
                count = 1

            else:
                total = (total + ((total-1)/2))*2
                count = 2
                tmptotal = total
        return int(total)

    n =int(input())
    print(getPattern(n))

所以，我希望在 py3 env 中解决这个错误。

Answer 1

在 python3 /中是浮点除法，因此您的total变量被制成浮点数。 python3 中的 python2 代码的等效代码是这样的：

def getPattern(n):
    total = 2
    tmptotal = 1
    count = 2

    if n == 1 or n == 2:
        print(n)
    else:
        for i in range(2, n):
            if count == 2:
                total = (total + (total // 2)) * 2 + 1
                count = 1

            else:
                total = (total + ((total - 1) // 2)) * 2
                count = 2
                tmptotal = total
        return total  # No cast needed

n = int(input())
print(getPattern(n))

$ python3 a.py
1000
330517704870201659222613814938036091491355508188037041916230092056707149336676224885194578462652015490977444424218145588987738645525154727966335681314488418506905056299580200969503693557241210318597600029397154510282236953905773609515391543263521668622626544531370086101386763599259723954366342063729034055207567140944645572557104099576971974229639101021224734402343310542961589984673879191254735147027265106522417859716025703587596412186791458002653591533043275692225713805000
$ python2 a.py
1000
330517704870201659222613814938036091491355508188037041916230092056707149336676224885194578462652015490977444424218145588987738645525154727966335681314488418506905056299580200969503693557241210318597600029397154510282236953905773609515391543263521668622626544531370086101386763599259723954366342063729034055207567140944645572557104099576971974229639101021224734402343310542961589984673879191254735147027265106522417859716025703587596412186791458002653591533043275692225713805000