solves #2194: Cells in a Range on an Excel Sheet in java

Author: anishLearnsToCode

Diff for: README.md

@@ -717,7 +717,7 @@
 | 2180 | [Count Integers With Even Digit Sum](https://leetcode.com/problems/count-integers-with-even-digit-sum)                                                                 |                                                                                [![Java](assets/java.png)](src/CountIntegersWithEvenDigitSum.java)                                                                                |                                                                                                                                   |
 | 2185 | [Counting Words With a Given Prefix](https://leetcode.com/problems/counting-words-with-a-given-prefix)                                                                 |                                                                                [![Java](assets/java.png)](src/CountingWordsWithAGivenPrefix.java)                                                                                |                                                                                                                                   |
 | 2190 | [Most Frequent Number Following Key In an Array](https://leetcode.com/problems/most-frequent-number-following-key-in-an-array)                                         |                                                                           [![Java](assets/java.png)](src/MostFrequentNumberFollowingKeyInAnArray.java)                                                                           |                                                                                                                                   |
-| 2194 | [Cells in a Range on an Excel Sheet](https://leetcode.com/problems/cells-in-a-range-on-an-excel-sheet)                                                                 |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2194 | [Cells in a Range on an Excel Sheet](https://leetcode.com/problems/cells-in-a-range-on-an-excel-sheet)                                                                 |                                                                                 [![Java](assets/java.png)](src/CellsInARangeOnAnExcelSheet.java)                                                                                 |                                                                                                                                   |
 | 2200 | [Find All K-Distant Indices in an Array](https://leetcode.com/problems/find-all-k-distant-indices-in-an-array)                                                         |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2206 | [Divide Array Into Equal Pairs](https://leetcode.com/problems/divide-array-into-equal-pairs)                                                                           |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2210 | [Count Hills and Valleys in an Array](https://leetcode.com/problems/count-hills-and-valleys-in-an-array)                                                               |                                                                                                                                                                                                                                  |                                                                                                                                   |

Diff for: src/CellsInARangeOnAnExcelSheet.java

@@ -0,0 +1,25 @@
+// https://leetcode.com/problems/cells-in-a-range-on-an-excel-sheet
+// T: O(1)
+// S: O(1)
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CellsInARangeOnAnExcelSheet {
+    public List<String> cellsInRange(String s) {
+        final char column1 = s.charAt(0);
+        final char column2 = s.charAt(3);
+        final int row1 = s.charAt(1) - '0';
+        final int row2 = s.charAt(4) - '0';
+
+        final List<String> result = new ArrayList<>();
+
+        for (char column = column1 ; column <= column2 ; column++) {
+            for (int row = row1 ; row <= row2 ; row++) {
+                result.add((column + "") + row);
+            }
+        }
+
+        return result;
+    }
+}