739. Daily Temperatures

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 i<sup>th</sup> 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 <= 10<sup>5</sup>

• 30 <= temperatures[i] <= 100

Solution:

class Solution:
    def dailyTemperatures(self, temperatures: List[int]) -> List[int]:
        res = [0] * len(temperatures)
        stack = []  # pair: (temp, index)

        for i, t in enumerate(temperatures):
            while stack and t > stack[-1][0]:
                stackT, stackInd = stack.pop()
                res[stackInd] = i - stackInd
            stack.append((t, i))
        return res