Find a number where it appears exactly N/2 times

Question

Here is one of my interview question. Given an array of N elements and where an element appears exactly N/2 times and the rest N/2 elements are unique

Answer 1

Restating my solution from a comment to Ganesh's version so I can format it:

for (i=0; i

Probability of winning after 1 iteration: 50%

Probability of winning after 2 iterations: 75%

Etc.

Worst case, O(n) time O(1) space.

Note that after N/4 iterations you've used up all the N/2 unique numbers, so this loop will never iterate through more than 3/4 of the array if it is as specified.