Find the element that appears once in an array

Find the element that appears only once in a given set of integers while all the other elements occur N times. Algorithm 1: 1: Create countSetBits[] array of size 32(for representing 32 bit integer) where, countSetBits[i] represents count of ith set bit of all elements in the input array. Initially all elements of countSetBits[] array are 0. 2: Traverse all the elements of the input array to populate countSetBits, by doing step #3 for each of them. 3: Take the element and check for its set bits. If the ith bit is found to be set, then in the countSetBits[] array increment the count of the element at the index 'i'. 4: After finishing the above operation for all the elements of the input array, the elements of countSetBits[] would represent count of all set bits in the elements of input array. Perform the modulus N operation on each element of the countSetBits[] array. Modules N operation will eliminate count of set bits of elements occurring N times. After the modulus N operation, if we get a remainder 1 at an index 'j', then that means in the number that occurs only once, we have a set bit at index 'j'. After the modulus N operation on each element, the countSetBits[] array represents bits representation of required element. Set individual bits in variable ‘solution’. Time Complexity: O(n) Space Complexity: O(1) Algorithm 2: 1: Initialize solution = 0. 2: Set individual bits of ‘solution’ by doing step #3. 3: To set ith bit position of ‘solution’, calculate sum of all of ith set bit of all elements in the input array, and mod it by N. Time Complexity: O(n) Space Complexity: O(1) Code and Algorithm Visualization: http://www.ideserve.co.in/learn/find-the-element-that-appears-once-in-an-array Website: http://www.ideserve.co.in Facebook: https://www.facebook.com/IDeserve.co.in