Why we use ^ operator

Question

Arr=[1,2,1,5,5]
Res=0
For i in arr:
Res ^=I
Print (res)

Question is to find number which is only once repeated

Answer 1

With integers ^ is a "bitwise exclusive or" operation (xor). The result in each bit position is 1 if bits of operands are differ in that bit position and 0 if they are the same.

If you do a xor operation on two equal numbers then the result will be zero.
2^2 = 0
If you do xor operation on any number and zero then the result will be the same number.
2^0 = 2

when you do xor operation in a loop on numbers which are duplicated even number of times, they all are zero out each other:
1^2^1^5^5 = (1^2^1)^5^5
xor is commutative operation
1^2^1 is the same as 1^1^2 ==> (1^1)^2
1^1 = 0
(1^1)^2 = 0^2 = 2
==> (1^2^1)^5^5 = 2^5^5
2^5^5 is the same as 5^5^2 ==> (5^5)^2
5^5=0
(5^5)^2 = 0^2 = 2

so the result is 2, the number that appears in the list only once

Answer 2

This a quick try and not perfect. But it's doing the job:

arr=[1,2,3,1,5,5,8]
res = []
for i in arr:
for j in arr:
if i ^ j == 0:
res.append(i)
if len(res) == 1:
print(f'number {res[0]} appears {len(res)} x')
res = []

# result is:
'''
number 2 appears 1 x
number 3 appears 1 x
number 8 appears 1 x
'''

Answer 3

Thank you so much.... andriy kan
For clear explanation.

Answer 4

Ok tq😊

Answer 5

Hima, from which approach are talking about? As we have multiple approaches here, it would be nice if you could specify it a bit. Thanks!
BTW, arr[]={1,2,3,10,11} is not a valid python expression that causes a syntax error.

Answer 6

Well there's a problem with your approach if the array is
arr[]={1,2,3,10,11}
as 3 in binary is 011
and 2 in binary is 010
outputs:1

Answer 7

Lothar taking xor with every array element. It's a C/C++ style array .

Answer 8

Xor operator works on bits
If odd no of inputs are then the result is true otherwise false.
Suppose you have two no 2 and 3
In binary , they are represented as 10 and 11
Now 10^11
2 = 10
3 = 11
01
Bit by bit manipulation takes place . That's why if there are two same no then there xor would be zero