solves surface area of 3d shapes

Author: anishLearnsToCode

Diff for: README.md

@@ -240,7 +240,7 @@
 | 883 | [Projection Area of 3D Shapes](https://leetcode.com/problems/projection-area-of-3d-shapes) | [![Java](assets/java.png)](src/ProjectionAreaOf3DShapes.java) |
 | 884 | [Uncommon Words from 2 Sentences](https://leetcode.com/problems/uncommon-words-from-two-sentences) | [![Java](assets/java.png)](src/UncommonWordsFromTwoSentences.java) |
 | 888 | [Fair Candy Swap](https://leetcode.com/problems/fair-candy-swap) | [![Java](assets/java.png)](src/FairCandySwap.java) |
-| 892 | [Surface Area of 3D Shapes](https://leetcode.com/problems/surface-area-of-3d-shapes) | |
+| 892 | [Surface Area of 3D Shapes](https://leetcode.com/problems/surface-area-of-3d-shapes) | [![Java](assets/java.png)](src/SurfaceAreaOf3DShapes.java) |
 | 893 | [Groups of Special Equivalent Strings](https://leetcode.com/problems/groups-of-special-equivalent-strings) | |
 | 896 | [Monotonic Array](https://leetcode.com/problems/monotonic-array) | |
 | 897 | [Increasing Order Search Tree](https://leetcode.com/problems/increasing-order-search-tree) | |

Diff for: src/SurfaceAreaOf3DShapes.java

@@ -0,0 +1,16 @@
+public class SurfaceAreaOf3DShapes {
+    public int surfaceArea(int[][] grid) {
+        final int rows = grid.length, columns = grid[0].length;
+        int surfaceArea = 0;
+        for (int row = 0 ; row < rows ; row++) {
+            for (int column = 0 ; column < columns ; column++) {
+                surfaceArea += (grid[row][column] > 0 ? 2 : 0)
+                        + (column + 1 < columns ? Math.abs(grid[row][column] - grid[row][column + 1]) : grid[row][column])
+                        + (row + 1 < rows ? Math.abs(grid[row][column] - grid[row + 1][column]) : grid[row][column])
+                        + (row == 0 ? grid[row][column] : 0)
+                        + (column == 0 ? grid[row][column] : 0);
+            }
+        }
+        return surfaceArea;
+    }
+}