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    <p>First, create indices that we will sort using the scores:</p> <pre><code>final double[] scores = // acquire scores Integer[] indices = new Integer[scores.length]; Arrays.sort(indexes, new Comparator&lt;Integer&gt;() { @Override public int compare(Integer i, Integer j) { return -Double.compare(scores[i], scores[j]); } }); </code></pre> <p>Note that we use a <code>-</code> to sort in <em>descending</em> order.</p> <p>Now, we have a ordered our scores using <code>indices</code>, and accounted for the possibility of repeated scores. Next, we will collect all the indices for each score. We will do this by building a map from scores to lists of indices for that score.</p> <pre><code>Map&lt;Double, SortedSet&lt;Integer&gt;&gt; map = new HashMap&lt;Double, SortedSet&lt;Integer&gt;&gt;(); for(int i = 0; i &lt; scores.length; i++) { if(!map.containsKey(scores[i])) { map.puts(scores[i], new TreeSet&lt;Integer&gt;()); } map.get(scores[i]).add(indexes[i] + 1); } </code></pre> <p>We use <code>SortedSet</code> so that the indices come out in order and we add <code>1</code> because your ranks start at one instead of zero.</p> <p>Now, if you iterate over the scores, you can look up the ranks from the <code>HashMap</code>.</p> <pre><code>for(int i = 0; i &lt; scores.length; i++) { SortedSet&lt;Integer&gt; set = map.get(scores[i]); System.out.print(scores[i] + ": "); Iterator&lt;Integer&gt; iterator = set.iterator(); System.out.print(iterator.next()); while(iterator.hasNext()) { System.out.print("," + iterator.next()); } System.out.println(); } </code></pre> <p>When I run this on your example <code>[40, 40, 10, 20]</code>, I see the output:</p> <pre><code>40: 1,2 40: 1,2 10: 3 20: 4 </code></pre> <p>and on <code>[40, 40, 40, 10]</code>:</p> <pre><code>40: 1,2,3 40: 1,2,3 40: 1,2,3 10: 4 </code></pre> <p>and on <code>[10, 10, 20, 40]</code>:</p> <pre><code>10: 3,4 10: 3,4 20: 2 40: 1 </code></pre> <p>From here, it should be easy to modify to get your desired rankings.</p> <p>Let's walk through how this works mentally. We'll use the example <code>[40, 40, 10, 20]</code>. First, we build indexes:</p> <pre><code>indexes = [0, 1, 2, 3] </code></pre> <p>Then we sort indexes using the scores;</p> <pre><code>indexes = [0, 1, 3, 2] </code></pre> <p>Then we collect all the ranks for each score (remember, we add one to the indexes from the previous step):</p> <pre><code>map = { 40 : [1, 2], 10 : [4], 20 : [3] } </code></pre> <p>Then, for each score in <code>scores</code>, we can look up all the ranks in <code>map</code> and dump them to the console.</p>
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