<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:
    // Using PQ TC->(NlogK)
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        int n=nums.size();
        vector<int>ans;
        priority_queue<pair<int,int>>pq;
        for(int i=0;i<n;i++){
            while(!pq.empty() && pq.top().first<=nums[i]){
                pq.pop();
            }
            pq.push({nums[i],i});
            if(i+1-k>=0){
                while(pq.top().second<i+1-k){
                    pq.pop();
                }
                ans.push_back(pq.top().first);
            }
        }
        return ans;
    }


    // Using DeQue TC->O(n)
    // vector<int> maxSlidingWindow(vector<int>& nums, int k) {
    //     int n=nums.size();
    //     vector<int>ans;
    //     deque<int>dq;
    //     for(int i=0;i<n;i++){
    //         while(!dq.empty() && nums[i]>nums[dq.back()]){
    //             dq.pop_back();
    //         }
    //         dq.push_back(i);
    //         if(i+1-k>=0){
    //             while(dq.front()<i+1-k){
    //                 dq.pop_front();
    //             }
    //             ans.push_back(nums[dq.front()]);
    //         }
    //     }
    //     return ans;
    // }
};
144033