title: Sorting 2-D array in descending order using lambda expression
body: <p>I am working through some interview questions and came across this one. I understand thoroughly the code except what the next line does:</p>
  
  <pre><code>Arrays.sort(pair, (a, b) -&gt; (b[0] - a[0]));
  </code></pre>
  
  <p><strong>Given scores of N athletes, find their relative ranks and the people with the top three highest scores, who will be awarded medals: "Gold Medal", "Silver Medal" and "Bronze Medal"</strong>.</p>
  
  <blockquote>
    <p>Example 1: Input: [5, 4, 3, 2, 1] Output: ["Gold Medal", "Silver
    Medal", "Bronze Medal", "4", "5"] Explanation: The first three
    athletes got the top three highest scores, so they got "Gold Medal",
    "Silver Medal" and "Bronze Medal".  For the left two athletes, you
    just need to output their relative ranks according to their scores.</p>
  </blockquote>
  
  <pre><code> public class Solution {
  
     public String[] findRelativeRanks(int[] nums) {
  
          int[][] pair = new int[nums.length][2];
  
          for (int i = 0; i &lt; nums.length; i++) {
              pair[i][0] = nums[i];
              pair[i][1] = i;
          }
  
          Arrays.sort(pair, (a, b) -&gt; (b[0] - a[0]));
  
          String[] result = new String[nums.length];
  
          for (int i = 0; i &lt; nums.length; i++) {
              if (i == 0) {
                  result[pair[i][1]] = "Gold Medal";
              }
              else if (i == 1) {
                  result[pair[i][1]] = "Silver Medal";
              }
              else if (i == 2) {
                  result[pair[i][1]] = "Bronze Medal";
              }
              else {
                  result[pair[i][1]] = (i + 1) + "";
              }
          }
  
          return result;
      }
  }
  </code></pre>