<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) {
        
        int k = nums.size(),i,j;
        int range = -1, left = 0, right = 0;

        set<int> st;
        for(auto v: nums){
            for(auto x: v){
                st.insert(x);
            }
        }

        int ansDiff = 1e9, ansLower = 0;

        for(auto ele : st){
            //cout<<ele<<endl;
            int mx = -1e9;
            for(i=0;i<k;i++){
                int siz = nums[i].size();
                int l = 0, r = siz-1;
                int cur = -1e9;

                while(l<=r){
                    int mid = l+(r-l)/2;

                    if(ele <= nums[i][mid]){
                        r = mid -1;
                        cur = nums[i][mid];
                    }
                    else{
                        l = mid + 1;
                    }
                }

                if(cur == -1e9){
                    break;
                }

                mx = max(mx,cur);
            }

            if(i == k){
                //cout<<"Hi "<<mx<<endl;
                if(ansDiff > (mx - ele)){
                //cout<<"Hig "<<mx-ele<<endl;

                    ansDiff = mx - ele;
                    ansLower = ele;
                }
            }
        }

        return {ansLower, ansDiff+ansLower};
    }
};
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