In binary number (python) 1 of

Title Description  

An integer that indicates the number of the output of the binary number 1 in. Wherein a negative number indicates a complement. (Here, only the leading 32)

-2 complement: first ones complement -2 10000 .. . 10 - "11111 .. . 01    

Then twos complement, i.e., the end of the inverted plus 1: 111 .. . 10     

method 1:

. 1  # - * - Coding: UTF-. 8 - * - 
2  class Solution:
 . 3      DEF NumberOf1 (Self, n-):
 . 4          COUNT = 0
 . 5          in front of n = n & 0xFFFFFFFF #python the number of how many bits we do not understand, taken 32 it
 . 6          for I in STR (bin (n-)):
 . 7              IF I == ' . 1 ' :
 . 8                  COUNT + =. 1
 . 9          return COUNT

Method 2:

# -*- coding:utf-8 -*-
class Solution:
    def NumberOf1(self, n):
        count = 0
        for i in range(32):
            mask = 1<<i
            if mask & n!=0:
                count+=1
        return count

 Method 3:  

1 class Solution:
2     def NumberOf1(self, n):
3         count=0
4         n = n&0xFFFFFFFF
5         while n>0:
6             n = n&(n-1)
7             count+=1
8         return count

2019-12-02 09:51:36