739-Daily-Temperatures.java

class Solution {

    public int[] dailyTemperatures(int[] temperatures) {
        int[] ans = new int[temperatures.length];
        Stack<Integer> stack = new Stack<>();
        for (int currDay = 0; currDay < temperatures.length; currDay++) {
            while (
                !stack.isEmpty() &&
                temperatures[currDay] > temperatures[stack.peek()]
            ) {
                int prevDay = stack.pop();
                ans[prevDay] = currDay - prevDay;
            }
            stack.add(currDay);
        }
        return ans;
    }
}