python二分法排序

#!/usr/bin/env python# -*- coding: utf-8 -*-def find2(lst, x):    n = len(lst)    m = n / 2    if lst[m] == x:            return m    elif lst[m] > x:            return find2(lst[:m], x)    else:            return m + 1 + find2(lst[m+1:], x)if __name__ == '__main__':a = [1, 2, 3, 4, 5]print find2(a, 3)