The code presented checks whether a year between 0 and 102499 is a leap year using only three CPU instructions, leveraging advanced bit manipulation techniques and mathematical optimizations to achieve this efficiency. The article explains the complexity behind these optimizations and provides insights into how traditional leap year checks can be significantly sped up by applying clever algorithms and magic numbers.

Branchless programming eliminates control flow branches in code to enhance performance by avoiding costly pipeline flushes in modern CPUs. By using arithmetic and bit manipulation instead of conditional jumps, programmers can create more efficient algorithms, especially in performance-critical applications. The article provides examples in C, demonstrating the advantages of branchless code for operations like calculating absolute values, clamping values, and partitioning arrays.