LeetCode-in-All
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
-spec daily_temperatures([integer()]) -> [integer()].
daily_temperatures(Temp) ->
{Result, _} = lists:mapfoldl(fun do_map_reduce/2, [], lists:zip(lists:reverse(Temp), lists:seq(0, length(Temp) - 1))),
lists:reverse(Result).
do_map_reduce({X, I}, [{Y, J} | Tail]) when X >= Y ->
do_map_reduce({X, I}, Tail);
do_map_reduce({X, I}, [{Y, J} | Tail]) ->
{I - J, [{X, I}, {Y, J} | Tail]};
do_map_reduce({X, I}, []) ->
{0, [{X, I}]}.