LeetCode in Elixir
739. Daily Temperatures
Medium
Given an array of integers temperatures represents the daily temperatures, return an array answer such that answer[i] is the number of days you have to wait after the ith day to get a warmer temperature. If there is no future day for which this is possible, keep answer[i] == 0 instead.
Example 1:
Input: temperatures = [73,74,75,71,69,72,76,73]
Output: [1,1,4,2,1,1,0,0]
Example 2:
Input: temperatures = [30,40,50,60]
Output: [1,1,1,0]
Example 3:
Input: temperatures = [30,60,90]
Output: [1,1,0]
Constraints:
1 <= temperatures.length <= 10530 <= temperatures[i] <= 100
Solution
defmodule Solution do
@spec daily_temperatures(temp :: [integer]) :: [integer]
def daily_temperatures(temp) do
Enum.reverse(temp)
|> Enum.with_index()
|> Enum.map_reduce([], &do_map_reduce/2)
|> elem(0)
|> Enum.reverse()
end
defp do_map_reduce({x, i}, [{y, j} | tail]) when x >= y do
do_map_reduce({x, i}, tail)
end
defp do_map_reduce({x, i}, [{y, j} | tail]) do
{i - j, [{x, i}, {y, j} | tail]}
end
defp do_map_reduce({x, i}, []) do
{0, [{x, i}]}
end
end