<p>You have <code>k</code> lists of sorted integers in <strong>non-decreasing&nbsp;order</strong>. Find the <b>smallest</b> range that includes at least one number from each of the <code>k</code> lists.</p>

<p>We define the range <code>[a, b]</code> is smaller than range <code>[c, d]</code> if <code>b - a &lt; d - c</code> <strong>or</strong> <code>a &lt; c</code> if <code>b - a == d - c</code>.</p>

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

<pre>
<strong>Input:</strong> nums = [[4,10,15,24,26],[0,9,12,20],[5,18,22,30]]
<strong>Output:</strong> [20,24]
<strong>Explanation: </strong>
List 1: [4, 10, 15, 24,26], 24 is in range [20,24].
List 2: [0, 9, 12, 20], 20 is in range [20,24].
List 3: [5, 18, 22, 30], 22 is in range [20,24].
</pre>

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

<pre>
<strong>Input:</strong> nums = [[1,2,3],[1,2,3],[1,2,3]]
<strong>Output:</strong> [1,1]
</pre>

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

<ul>
	<li><code>nums.length == k</code></li>
	<li><code>1 &lt;= k &lt;= 3500</code></li>
	<li><code>1 &lt;= nums[i].length &lt;= 50</code></li>
	<li><code>-10<sup>5</sup> &lt;= nums[i][j] &lt;= 10<sup>5</sup></code></li>
	<li><code>nums[i]</code>&nbsp;is sorted in <strong>non-decreasing</strong> order.</li>
</ul>

class Solution {
public:
    vector<int> smallestRange(vector<vector<int>>& nums) {
        priority_queue<vector<int>,vector<vector<int>>,greater<vector<int>>>pq;
        priority_queue<int>pq1;
        for(int i=0;i<nums.size();i++){
            pq.push({nums[i][0],0,i});
            pq1.push(nums[i][0]);
        }
        vector<int>range(2);
        auto ele=pq.top();
        range[0]=ele[0];
        range[1]=pq1.top();
      while(!pq.empty()){
            auto it=pq.top();
            pq.pop();
            // if(range[1]-range[0])
            int iarraysize=nums[it[2]].size();
            if(it[1]==iarraysize-1){
                break;
            }
            pq.push({nums[it[2]][it[1]+1],it[1]+1,it[2]});
            if(pq1.top()<nums[it[2]][it[1]+1]){
                pq1.push(nums[it[2]][it[1]+1]);
            }

            int newrange=pq1.top()-pq.top()[0];
             int prevdiff=range[1]-range[0];
             if(newrange<prevdiff){
                range[0]=pq.top()[0];
                range[1]=pq1.top();
             }

      }
      return range;
        
    }
};
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