/**
 * 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 <= 10^5
 * 30 <= temperatures[i] <= 100
 * @see <a href="https://leetcode.com/problems/daily-temperatures/">LeetCode</a>
 */
fun dailyTemperatures(temperatures: IntArray): IntArray {
    val stack = ArrayDeque<Pair<Int, Int>>()
    val answer = IntArray(temperatures.size)

    for (index in (0 until temperatures.size).reversed()) {
        while (stack.isNotEmpty() && temperatures[index] >= stack.last().first) {
            stack.removeLast()
        }
        answer[index] = if (stack.isEmpty()) 0 else stack.last().second - index
        stack.add(Pair(temperatures[index], index))
    }
    return answer
}
