739. Daily Temperatures

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].

class Solution {public:    vector<int> dailyTemperatures(vector<int>& T) {        vector<int> ans(T.size());        if (T.size() == 0) {            return ans;        }        stack<int> st;        for (int i = T.size() - 1; i >= 0; i--) {            while (!st.empty() && T[st.top()] <= T[i]) {                st.pop();            }            if (!st.empty()) {                int top = st.top();                ans[i] = top - i;            } else {                ans[i] = 0;            }            st.push(i);        }
        return ans;    }};