PreviousNext
Coding/Arrays and strings

Track the record high price on every day

Write codeEasy10 min

Your task

Wholesale electricity prices change every day, and they can drop below zero when supply far outruns demand. A trading dashboard shows, for each day, the highest price seen so far.

Write record_highs(prices) that returns that record high for every day.

Input and output:

  • prices: a list of up to 100,000 daily prices in date order, each an integer between -1,000,000 and 1,000,000. It may be empty.
  • Returns a list of integers, the same length as prices.

Rules:

  • Position i of the result holds the highest price from day 0 to day i, including day i itself.
  • An empty list returns an empty list.

Examples

record_highs(prices: list[int]) -> list[int]
Example 1
Inputrecord_highs([3, 1, 4, 2, 6])
Output[3, 3, 4, 4, 6]
Example 2
Inputrecord_highs([-5, -8, -2, -9])
Output[-5, -5, -2, -2]
Example 3
Inputrecord_highs([0, -3, 4, 4, -1])
Output[0, 0, 4, 4, 4]