Group By Average
MediumData EngineeringArrayMathSorting
Description
Given an array of [key, value] pairs, group by key and return [key, average] for each distinct key, where average is the mean of that key’s values rounded to 4 decimal places. Order the groups by each key’s first appearance.
Examples
Input:
[[1,10],[1,20],[2,30]]Output:
[[1,15],[2,30]]Explanation:
Rows sharing a key are collapsed into one carrying the average of their values, with keys ordered by first appearance.
Input:
[[5,2],[5,4],[5,6]]Output:
[[5,4]]Explanation:
Rows sharing a key are collapsed into one carrying the average of their values, with keys ordered by first appearance.
Input:
[[1,1],[2,2],[3,3]]Output:
[[1,1],[2,2],[3,3]]Explanation:
Rows sharing a key are collapsed into one carrying the average of their values, with keys ordered by first appearance.
Constraints
- •
1 ≤ number of pairs ≤ 10⁴