<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>

#include <vector>
#include <algorithm>
#include <limits.h>

class Solution {
public:
    std::vector<int> arrayRankTransform(std::vector<int>& arr) {
        std::vector<int> res(arr.size());
        if (arr.empty()) return res;

        int max_val = INT_MIN;
        int min_val = INT_MAX;

        // Find the minimum and maximum values in the array
        for (int val : arr) 
        {
            max_val = std::max(val, max_val);
            min_val = std::min(val, min_val);
        }

        if (max_val - min_val > 200 && arr.size() < 10) 
        {
            std::vector<int> tmp = arr;
            std::sort(arr.begin(), arr.end());

            int index = 1;
            bool isRepeat = false;

            for (size_t i = 0; i < arr.size(); ++i) 
            {
                int val = arr[i];
                isRepeat = false;

                for (size_t j = 0; j < tmp.size(); ++j) 
                {
                    if (tmp[j] == val) 
                    {
                        if (isRepeat) 
                        {
                            i++;
                        }
                        res[j] = index;
                        isRepeat = true;
                    }
                }
                index++;
            }

            return res;
        } 
        else 
        {

            std::vector<int> nums(max_val - min_val + 1, 0);

            for (int i = 0; i < arr.size(); ++i) 
            {
                nums[arr[i] - min_val] = 1;
            }
            int rank = 1;
            for (int i = 0; i < max_val - min_val + 1; ++i) 
            {
                if (nums[i] == 1) 
                {
                    nums[i] = rank++;
                }
            }
            for (int i = 0; i < arr.size(); ++i) 
            {
                res[i] = nums[arr[i] - min_val];
            }

            return res;
        }
    }
};

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