<p>Given an array of integers&nbsp;<code>arr</code>, replace each element with its rank.</p>

<p>The rank represents how large the element is. The rank has the following rules:</p>

<ul>
	<li>Rank is an integer starting from 1.</li>
	<li>The larger the element, the larger the rank. If two elements are equal, their rank must be the same.</li>
	<li>Rank should be as small as possible.</li>
</ul>

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

<pre>
<strong>Input:</strong> arr = [40,10,20,30]
<strong>Output:</strong> [4,1,2,3]
<strong>Explanation</strong>: 40 is the largest element. 10 is the smallest. 20 is the second smallest. 30 is the third smallest.</pre>

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

<pre>
<strong>Input:</strong> arr = [100,100,100]
<strong>Output:</strong> [1,1,1]
<strong>Explanation</strong>: Same elements share the same rank.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> arr = [37,12,28,9,100,56,80,5,12]
<strong>Output:</strong> [5,3,4,2,8,6,7,1,3]
</pre>

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

<ul>
	<li><code>0 &lt;= arr.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>9</sup>&nbsp;&lt;= arr[i] &lt;= 10<sup>9</sup></code></li>
</ul>

class Solution {
public:
    vector<int> arrayRankTransform(vector<int>& arr) {
        unordered_map<int,int> m;
        vector<int> a= arr;
        sort(a.begin(), a.end());
        int rank=1;
        for(int i=0; i<a.size(); i++){
            int b= a[i];
           // Assign rank only if the element is not already present in the map
            if (m.find(b) == m.end()) {
                m[b] = rank;
                rank++;
            }
        }

        vector<int> rel;
        for(int i=0; i<arr.size(); i++){
            rel.push_back(m[arr[i]]);
        }
        return rel;
    }
};
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