LeetCode 238 ·
Medium
Product of Array Except Self
Return an array where each element is the product of all the others, without using division.
Try it
Step through the core mechanic. The simulator below runs the math shape this problem is built on.
Walk the pattern
No dedicated step-through for this one yet. The shape is Math — its pattern page has the interactive walkthrough, the reference implementation, and a five-problem progression that this problem sits inside.
The approach
Two passes: a left-to-right prefix product, then a right-to-left suffix product folded into the same output array. The prefix and suffix sweeps each contribute one side of the product.
| Aspect | Value |
|---|---|
| Pattern | Math |
| Recognise it by | Answer[i] depends on everything but i; no division allowed. |
| Time complexity | O(n) |
| Space complexity | O(1) |
| Difficulty | Medium |
Who asks it
Companies known to ask this problem, from public LeetCode company-tag aggregations. A signal of where to expect it, not a guarantee.