Merge pull request #901 from FridaTveit/SaddlePointsImplementComparable

saddle-points: make MatrixCoordinate implement Comparable

exercises/saddle-points/.meta/src/reference/java/MatrixCoordinate.java

-class MatrixCoordinate {
+class MatrixCoordinate implements Comparable<MatrixCoordinate> {
     private final int row;
     private final int col;
 
         result = 31 * result + col;
         return result;
     }
+
+    @Override
+    public int compareTo(MatrixCoordinate o) {
+        int rowComparison = Integer.compare(row, o.row);
+        return (rowComparison == 0) ? Integer.compare(col, o.col) : rowComparison;
+    }
 }

exercises/saddle-points/src/main/java/MatrixCoordinate.java

-class MatrixCoordinate {
+class MatrixCoordinate implements Comparable<MatrixCoordinate> {
     private final int row;
     private final int col;
 
         result = 31 * result + col;
         return result;
     }
+
+    @Override
+    public int compareTo(MatrixCoordinate o) {
+        int rowComparison = Integer.compare(row, o.row);
+        return (rowComparison == 0) ? Integer.compare(col, o.col) : rowComparison;
+    }
 }