Advantages of bitwise exclusive or operations

The previous log talked about bit operations.

 

Bit operators:

(1 ),~ Reverse retrieval ~ 0011 = 1100

(2), & bits and 0011 & 0110 = 0010

(3), | bit or 0011 | 0110 = 0111

(4) ^ exclusive or 0011 ^ 0110 = 0101

 

 

There are two questions about the advantages of bitwise OR (^) operations:

1. An array with a known length of 2n + 1. Each number in the array appears twice. Only one number X is unique. Find the separate number X?

First, let's talk about some knowledge points: a ^ A = 0; 0 ^ x = X;

Therefore, the solution is to perform an exclusive or operation on all the numbers in the array. A1 ^ A2 · x · = 0 ^ x = X;

 

2. An array a [10000] is known, and a number X is taken from it. Then, B [9999] is obtained, and the value of X is calculated?SpaceThe complexity requirement is O (1 ).

Solution:

A1 ^ A2 · a10000 = b1 ^ B2 · b9999 ^ X;

A1 ^ A2 · a10000 ^ B1 ^ B2 · b9999 = b1 ^ B2 · b9999 ^ x ^ B1 ^ B2 · b9999 = 0 ^ x = x;