739. Daily Temperatures

class Solution {
    public int[] dailyTemperatures(int[] temperatures) {
        int[] res = new int[temperatures.length];

        Stack<Integer> decreaseStack = new Stack<>(); // 非严格单调递减栈，栈中存储的为天的索引
        for (int i = 0; i < temperatures.length; i++) {
            while (!decreaseStack.isEmpty() && temperatures[i] > temperatures[decreaseStack.peek()]) {
                // 出现了更高的温度，此时记录
                int prevIndex = decreaseStack.pop();
                res[prevIndex] = i - prevIndex;
            }

            decreaseStack.push(i);
        }

        return res;
    }
}

Reference

739. Daily Temperatures
剑指 Offer II 038. 每日温度