Small exercise of solving a simple problem with different algorithms and measure their efficiency.
The task is: find the missing number from an array of unique positive integers ranging from 1 to the actual array size.
Examples:
- [3, 4, 2] -> missing number is 1
- [2, 6, 1, 3, 5] -> missing number is 4
- [1, 2, 5, 4, 3, 6] -> missing number is 7