LeetCode 739. Daily Temperatures

Question

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.

https://leetcode.com/problems/daily-temperatures/

class Solution {
    public int[] dailyTemperatures(int[] temperatures) {
        int n = temperatures.length, res[] = new int[n];
        Stack<Integer> stack = new Stack<>();
        for (int i = n - 1; i >= 0; i--){
            while (!stack.isEmpty() && temperatures[i] >= temperatures[stack.peek()]) stack.pop();
            res[i] = stack.isEmpty() ? 0 : stack.peek() - i;
            stack.push(i);
        }
        return res;
    }
}

Time complexity: O(n)

Space complexity: O(n)