Python求解排列中的逆序数个数实例

def inverse_number(string):
  'input a number which is string than,you will get the inverse number'
  ans = 0
  for i in range(len(string)):
    for j in range(i):
      if string[j] > string[i]:
        ans += 1
  return ans

print(inverse_number(input("Please input the number: ")))

# -*- coding:utf-8 -*-

class Solution:
  def NumberOf1(self, n):
    # write code here
    cnt = 0
    if n<0:
      n = n & 0xffffffff
    while n:
      cnt+=1
      n = (n-1) & n
    return cnt