Daily Temperatures
Description: Given daily temperatures, for each day return how many days until a warmer temperature. If there is none, put 0.
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]
Constraints:
1 <= temperatures.length <= 10⁵
30 <= temperatures[i] <= 100
Recommended time and space complexity
Aim for O(n) time and O(n) space.
Hint 1
Brute force over pairs is O(n²). Can you do a single pass?
Hint 2
Keep indices of days whose answer is not known yet in a stack.
Hint 3
When a warmer day arrives, you found the answer for the stack top. Pop while current is warmer.