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    <p>Java does not allow subindexing of arrays.</p> <p>What you are referring to is trivially possible in C, but in Java you will need to either:</p> <ul> <li>copy the data to new arrays</li> <li>use a custom class abstracting from storage.</li> </ul> <p>In java, there is no way that <code>foo[0]</code> <em>permanently refers</em> to the element <code>bar[3]</code> of another array.</p> <p>If you want to work with <code>int[][]</code>, you'll have to copy the arrays. <code>Arrays.copyOfRange</code> and <code>System.arraycopy</code> will be the most efficient choices, but at Sudoku size it does obviously not make much of a difference.</p> <p>For the second approach, write a custom <code>Matrix</code> class. For example</p> <pre><code>class Matrix { int[] flatStorage; int[] offsets; Matrix(int[] flatStorage, int[] offsets) { this.flatStorage = flatStorage; this.offsets = offsets; } void set(int x, int y, int val) { flatStorage[ offsets[x] + y ] = val; } int get(int x, int y) { return flatStorage[ offsets[x] + y ]; } } int[] sharedStorage = new int[27]; Arrays.fill(sharedStorage, -1); // Initialize with -1 int[] allOffsets = new int[]{0,9,18, 27,36,45, 54,63,72}; Matrix nineByNine = new Matrix(sharedStorage, allOffsets); Matrix northEast = new Matrix(sharedStorage, new int[]{6,15,24}); Matrix southEast = new Matrix(sharedStorage, new int[]{60,69,78}); nineByNine.set(1,7, 2); // Write to middle of upper right quadrant System.err.println(northEast.get(1, 1)); // Read - should be 2! </code></pre> <p>Add size information and similar things yourself.</p>
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    1. POSplit 2D array into array of multiple smaller arrays?
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    1. COHaha, I remember when I was starting I tried to sublist an array like it would have been done in python. Years later, a few buddies and I are adding this in to a language similar to Java haha. I like the OOP approach to this method. Very clean code
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