179. Update Bits
- 本题难度: Medium
- Topic: Bit Manipulation
Description
Given two 32-bit numbers, N and M, and two bit positions, i and j. Write a method to set all bits between i and j in N equal to M (e g , M becomes a substring of N start from i to j)
Example
Given N=(10000000000)2, M=(10101)2, i=2, j=6
return N=(10001010100)2
Challenge
Minimum number of operations?
Clarification
You can assume that the bits j through i have enough space to fit all of M. That is, if M=10011, you can assume that there are at least 5 bits between j and i. You would not, for example, have j=3 and i=2, because M could not fully fit between bit 3 and bit 2.
Notice
In the function, the numbers N and M will given in decimal, you should also return a decimal number.
别人的代码
class Solution:
"""
@param n: An integer
@param m: An integer
@param i: A bit position
@param j: A bit position
@return: An integer
"""
def updateBits(self, n, m, i, j):
# write your code here
tmp = ((~((((-1) << (31 - j) & 0xFFFFFFFF) >> (31 - j + i)) << i)) & 0xFFFFFFFF) & n | ((m << i) & 0xFFFFFFFF)
if tmp & (1 << 31):
return tmp ^ ~(0xFFFFFFFF)
return tmp
思路
实在不会,python做位运算好难哦