<p>You are given an array of integers&nbsp;<code>nums</code>, there is a sliding window of size <code>k</code> which is moving from the very left of the array to the very right. You can only see the <code>k</code> numbers in the window. Each time the sliding window moves right by one position.</p>

<p>Return <em>the max sliding window</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,3,-1,-3,5,3,6,7], k = 3
<strong>Output:</strong> [3,3,5,5,6,7]
<strong>Explanation:</strong> 
Window position                Max
---------------               -----
[1  3  -1] -3  5  3  6  7       <strong>3</strong>
 1 [3  -1  -3] 5  3  6  7       <strong>3</strong>
 1  3 [-1  -3  5] 3  6  7      <strong> 5</strong>
 1  3  -1 [-3  5  3] 6  7       <strong>5</strong>
 1  3  -1  -3 [5  3  6] 7       <strong>6</strong>
 1  3  -1  -3  5 [3  6  7]      <strong>7</strong>
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [1], k = 1
<strong>Output:</strong> [1]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>4</sup> &lt;= nums[i] &lt;= 10<sup>4</sup></code></li>
	<li><code>1 &lt;= k &lt;= nums.length</code></li>
</ul>

// class Solution {
// public:
//     vector<int> maxSlidingWindow(vector<int>& nums, int k) {
//         priority_queue<pair<int, int>> pq;
        
//         vector<int> ans;
//         ans.reserve(nums.size() - k+1);
//         for(int i=0; i<nums.size(); ++i)
//         {
//             pq.push({nums[i], i});

//             if(i>=k-1)
//             {
//                 while(!pq.empty() && pq.top().second <= (i-k))
//                 {
//                     pq.pop();
//                 }
//                 ans.emplace_back(pq.top().first);
//             }
//         }

//         return ans;
//     }
// };

class Solution {
public:
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        int q[nums.size()];
        int l = 0, r = 0;
        
        for (int idx = 0; idx < nums.size(); ++idx) {
            while (l < r && q[r - 1] < nums[idx]) {
                --r;
            }
            q[r++] = nums[idx];
            
            if (idx >= k - 1) {
                bool rm = q[l] == nums[idx - k + 1];
                nums[idx - k + 1] = q[l];
                if (rm) {
                    ++l;
                }
            }
        }
        
        nums.resize(nums.size() - k + 1);

        return nums;
    }
};
130923