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]`

.

**Solution:**

Iterate backwards and maintain a stack, pop until stack top is more than current element.

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