Array / String· 25 min

Product of Array Except Self

LeetCode #238 · Medium · Interactive step-by-step visualization

Setup

Example inputnums = [1, 2, 3, 4]
Step 1 / 18

Current step

1 / 18

Start a prefix pass. The answer at each index first receives the product strictly to its left. Prefix starts at 1.

Step log

nums

Cursor
1
0
2
1
3
2
4
3

answer

1
0
1
1
1
2
1
3

prefix

1

Active cursor
Comparing
Best or completed
Leaving or removed
product-of-array-except-self.java
1public int[] productExceptSelf(int[] nums) {
2    int[] answer = new int[nums.length];
3    int prefix = 1;
4    for (int i = 0; i < nums.length; i++) {
5        answer[i] = prefix;
6        prefix *= nums[i];
7    }
8    int suffix = 1;
9    for (int i = nums.length - 1; i >= 0; i--) {
10        answer[i] *= suffix;
11        suffix *= nums[i];
12    }
13    return answer;
14}
● Java
Time
O(n)
Space
O(1) extra
Pattern
array scan
Frames
18
7 / 75