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].

这道题从如果从前向后计算，那么时间复杂度就是n的平方了，如果从后面计算时间复杂度可以说是O(n).详细解法过程Clean code with explanation: O(n) time and O(1) space (beats 99.13%)

class Solution {
public:
    vector<int> dailyTemperatures(vector<int>& T) {
        int n = T.size();
        vector<int> res(n,0);
        for(int i = n - 1;i >= 0;i--)
        {
            int j = i + 1;
            while((j < n) && (T[i] >= T[j]))
            {
                (res[j] > 0) ? (j += res[j]):(j = n);
            }
            
            if(j < n) 
            {
                res[i] = j - i;
            }
        }
        return res;
    }
};