<p>Given an array of integers <code>temperatures</code> represents the daily temperatures, return <em>an array</em> <code>answer</code> <em>such that</em> <code>answer[i]</code> <em>is the number of days you have to wait after the</em> <code>i<sup>th</sup></code> <em>day to get a warmer temperature</em>. If there is no future day for which this is possible, keep <code>answer[i] == 0</code> instead.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> temperatures = [73,74,75,71,69,72,76,73]
<strong>Output:</strong> [1,1,4,2,1,1,0,0]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> temperatures = [30,40,50,60]
<strong>Output:</strong> [1,1,1,0]
</pre><p><strong class="example">Example 3:</strong></p>
<pre><strong>Input:</strong> temperatures = [30,60,90]
<strong>Output:</strong> [1,1,0]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;=&nbsp;temperatures.length &lt;= 10<sup>5</sup></code></li>
	<li><code>30 &lt;=&nbsp;temperatures[i] &lt;= 100</code></li>
</ul>

class Solution {
public:
    vector<int> dailyTemperatures(vector<int>& temperatures) {
        vector<int> res (temperatures.size());

        // <temp, index>
        vector<pair<int,int>> stack;

        for (int i = 0; i < temperatures.size(); ++i)
        {
            if (stack.size() == 0)
            {
                stack.push_back({temperatures[i], i});
            }
            else
            {
                while (stack.size() && stack[stack.size() - 1].first < temperatures[i])
                {
                    auto peekd = stack[stack.size() - 1];
                    stack.pop_back();
                    res[peekd.second] = i - peekd.second;
                }
                stack.push_back({temperatures[i], i});
            }
        }

        while (stack.size())
        {
            auto peekd = stack[stack.size() - 1];
            stack.pop_back();
            res[peekd.second] = 0;
        }

        return res;
    }
};
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