Early Exit Optimization

Early exit stops work as soon as the answer is known—break when found, short-circuit boolean checks, or returning on first violation. It cuts average time even when worst case stays the same.

Why this shows up in the real world

Security scanners abort a rule pack after critical failure. Search UIs stop highlighting after first N matches.

Core idea (explained for students)

Reorder conditions so cheapest checks run first. In loops, combine validation with return instead of extra passes.

Try this in Python

def has_negative(a: list[int]) -> bool:
    for x in a:
        if x < 0:
            return True
    return False


print(has_negative([1, 2, -1, 5]))

Common mistakes

• Exiting without restoring invariants needed by finally blocks.
• Micro-optimizing exits while leaving a dominant O(n²) core.

Key takeaways

• Measure: early exit helps average case; document worst case separately.
• Use guard clauses at function top for invalid input.