﻿ Python: Find the single element in a list where every element appears three times except for one - w3resource

# Python Challenges: Find the single element in a list where every element appears three times except for one

## Python Challenges - 1: Exercise-13 with Solution

Write a Python program to find the single element in a list where every element appears three times except for one.

Explanation:

Sample Solution:-

Python Code:

def single_number(arr):
ones, twos = 0, 0
for x in arr:
ones, twos = (ones ^ x) & ~twos, (ones & x) | (twos & ~x)
assert twos == 0
return ones
arr1 = [5, 3, 4, 3, 5, 5, 3]
arr2 = [-1, 1, 1, -1, -1, 1, 0]
print(single_number(arr1))
print(single_number(arr2))

Sample Output:

4
0

Flowchart:

Python Code Editor:

def single_number(arr):
ones, twos = 0, 0
for x in arr:
ones, twos = (ones ^ x) & ~twos, (ones & x) | (twos & ~x)
assert twos == 0
return ones
arr1 = [5, 3, 4, 3, 5, 5, 3]
arr2 = [-1, 1, 1, -1, -1, 1, 0]
print(single_number(arr1))
print(single_number(arr2))

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