Given an array of positive integers. All numbers occur even number of times except one number which occurs odd number of times. Find the number in O(n) time & constant space. Examples:
Input : [1, 2, 3, 2, 3, 1, 3] Output : 3
We have existing solution for this problem please refer Find the Number Occurring Odd Number of Times link. we will solve this problem in python quickly using Reduce(expression, iterable) method.
# Python program to Find the Number
# Occurring Odd Number of Times
# using Lambda expression and reduce function
from functools import reduce
def oddTimes(input):
# write lambda expression and apply
# reduce function over input list
# until single value is left
# expression reduces value of a ^ b into single value
# a starts from 0 and b from 1
# ((((((1 ^ 2)^3)^2)^3)^1)^3)
print (reduce(lambda a, b: a ^ b, input))
# Driver program
if __name__ == "__main__":
input = [1, 2, 3, 2, 3, 1, 3]
oddTimes(input)
Output:
3
Time complexity: O(n)
Auxiliary space: O(1)
