<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>

#include<bits/stdc++.h>
#include <queue>
using namespace std;

class Solution {
private:
    class Compare{
    public : 
        bool operator()( pair<int,int> a, pair<int,int> b){
            if ( a.first > b.first ){
                return true;
            } else if ( a.first == b.first ){
                return a.second > b.second ;
            }
            return false;
        }
    };
public:
    vector<int> maxSlidingWindow(vector<int>& nums, int k) {
        priority_queue<pair<int,int>, vector<pair<int,int>>, Compare> window;
        set<int> removed;
        vector<int> maxRange;
        
        for ( int i = 0; i < (int)nums.size(); i++ )
            nums[i] *= -1;

        int n = nums.size();

        for ( int i = 0; i < k; i++ )
            window.emplace(nums[i],i);

        for ( int i = k; i <= n; i++ ){
            while (!window.empty() && removed.find(window.top().second) != removed.end()) {
                pair<int, int> data = window.top();
                cout << data.first << " " << data.second << endl;
                window.pop();
            }
            pair<int,int> data = window.top();

            maxRange.emplace_back(-data.first);
            
            if ( nums[i-k] == data.first ){
                window.pop();
            }

            removed.emplace(i - k);
            if ( i < n )
                window.emplace(nums[i],i);
        }

        return maxRange;
    }
};
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