LeetCode : 739. Daily Temperatures. 日常温度-蒲公英云

LeetCode : 739. Daily Temperatures. 日常温度

试题
Given a list of daily temperatures T, return a list such that, for each day in the input, tells you how many days you would have to wait until a warmer temperature. If there is no future day for which this is possible, put 0 instead.

For example, given the list of temperatures T = [73, 74, 75, 71, 69, 72, 76, 73], your output should be [1, 1, 4, 2, 1, 1, 0, 0].

Note: The length of temperatures will be in the range [1, 30000]. Each temperature will be an integer in the range [30, 100].

代码
这利用了栈的一个非常好的特性，就是我们可以根据弹入的数据找到一个单调递增的数列。
当我们从后往前押入栈时，如果栈内数据小于当前数据，就可以直接弹出，这样我们就找到比当前数据大的第一个数据。

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