Why not ternary search

If x is present in right one-third. If x is present in middle one-third. We reach here when element is not present in array. Previous Exponential Search. Next Ternary Search. Recommended Articles. Unbounded Binary Search Example Find the point where a monotonically increasing function becomes positive first time.

Article Contributed By :. Easy Normal Medium Hard Expert. Writing code in comment? Please use ide. Load Comments. Learn more. Why use binary search if there's ternary search?

Ask Question. Asked 11 years, 3 months ago. Active 6 years ago. Viewed 20k times. Improve this question. Abel What if the array only has two elements?

Surprisingly all the answers only talk about time complexity. Space complexity is just as important in many cases and Ternary trees are generally more space efficient. And, given modern CPU architecture, space complexity often has a significant impact on actual performance.

I appreciate this is a 6-years old question. What you describe is not a ternary search, could someone please edit the title? FYI a ternary search is for unimodal functions, and binary for monotonic. Add a comment. Active Oldest Votes. Actually, people do use k-ary trees for arbitrary k. This is, however, a tradeoff. Improve this answer.

Borealid Borealid B-trees are k-ary trees that sit between arrays and binary trees, and are commonly used; there's certainly a purpose for k-ary trees that are larger than order 3. Binary is pretty close to that. Cucu but isn't Ternary closer? It is closer. But since the difference is not that big, simplicity of implementation gets more important, so binary wins. Svante Akusete Akusete There is only ever a constant factor difference between any two logarithmic orders of complexity.

Michael Burr Michael Burr k 49 49 gold badges silver badges bronze badges. The fact that a 'k-ary compare' in fact consists in 'k' key comparisons is possibly the most important factor to be mentioned in answering this question. I had no idea there were different meaning for 'a billion' until now. Akusete: A billion here and a billion there MichaelBurr: I'm afraid binary search in an array of 1 billion records takes an average of about 30 comparisons, not 15 ;- — chqrlie.

The top voted answers miss the boat on this one, I think. Reviewing: Ternary trees aren't supported by hardware, so they run less quickly. B-tress with orders much, much, much higher than 3 are common for disk-optimization of large datasets; once you've gone past 2, go higher than 3. Dean J Dean J A binary tree has two binary operations if less go left JB , if more go right JA. Whether the processor has binary or ternary architectures has nothing to do with it.

What makes you think Ternary search should be faster? So it looks like ternary search is worse. Community Bot 1 1 1 silver badge.

Aryabhatta Aryabhatta. I do not always need to make 2 comparisons at a level. For example - if I have [.. Lazer: He did say 'worst case'. Assuming a balanced tree, and an even distribution of lookups shakey assumption , you would need 1.

I'm not sure if we are interested in worst case, but rather in, how long does it take on average. This can't be right: the worst case is not the average case for binary search, because you only go down to the last iteration if you didn't find it on previous iterations.

Half the time, you won't make it to the last iteration, so something is certainly amiss here. As you get closer and closer to n, it gets even worse. Not only will the worst case scenario be improved with binary search, but your average time will be improved as well.

Looking at expected value what portion of the list can we remove on average , we use this formula:. Please note the log N vs 2 log N comparisons argument is based on a naive interpretation of the algorithm.

If I were to actually sit down and write this in x86 assembly the results would be inverted. The problem is the use of integers for test cases combined with an insufficiently smart compiler that can't remove the redundant comparisons. Retry with strings and an appropriate string comparison function, and code it to call the comparison function once per loop and you will find the ternary search is faster again.

Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. Why is binary search faster than ternary search? Ask Question. Asked 7 years, 2 months ago.

Active 9 months ago. Viewed 27k times. It seems that ternary search is faster, so why do we use binary search? Improve this question. David Richerby Or even decimal search If using a 3-based search is faster because it cuts the search space more at each iteration, then isn't using a million-based search faster?