solves #2124: Check if All A's Appears Before All B's in java

Author: anishLearnsToCode

Diff for: README.md

@@ -703,7 +703,7 @@
 | 2108 | [Find First Palindromic String in the Array](https://leetcode.com/problems/find-first-palindromic-string-in-the-array)                                                 |                                                                              [![Java](assets/java.png)](src/FindFirstPalindromicStringInArray.java)                                                                              |                                                                                                                                   |
 | 2114 | [Maximum Number of Words Found in Sentences](https://leetcode.com/problems/maximum-number-of-words-found-in-sentences)                                                 |                                                                            [![Java](assets/java.png)](src/MaximumNumberOfWordsFoundInSentences.java)                                                                             |                                                                                                                                   |
 | 2119 | [A Number After a Double Reversal](https://leetcode.com/problems/a-number-after-a-double-reversal)                                                                     |                                                                                 [![Java](assets/java.png)](src/ANumberAfterADoubleReversal.java)                                                                                 |                                                                                                                                   |
-| 2124 | [Check if All A's Appears Before All B's](https://leetcode.com/problems/check-if-all-as-appears-before-all-bs)                                                         |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2124 | [Check if All A's Appears Before All B's](https://leetcode.com/problems/check-if-all-as-appears-before-all-bs)                                                         |                                                                             [![Java](assets/java.png)](src/CheckIfAllTheAsAppearBeforeAllTheBs.java)                                                                             |                                                                                                                                   |
 | 2129 | [Capitalize the Title](https://leetcode.com/problems/capitalize-the-title)                                                                                             |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2133 | [Check if Every Row and Column Contains All Numbers](https://leetcode.com/problems/check-if-every-row-and-column-contains-all-numbers)                                 |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2138 | [Divide a String Into Groups of Size k](https://leetcode.com/problems/divide-a-string-into-groups-of-size-k)                                                           |                                                                                                                                                                                                                                  |                                                                                                                                   |

Diff for: src/CheckIfAllTheAsAppearBeforeAllTheBs.java

@@ -0,0 +1,14 @@
+// https://leetcode.com/problems/check-if-all-as-appears-before-all-bs
+// T: O(|s|)
+// S: O(1)
+
+public class CheckIfAllTheAsAppearBeforeAllTheBs {
+    public boolean checkString(String s) {
+        boolean seenB = false;
+        for (int index = 0 ; index < s.length() ; index++) {
+            if (s.charAt(index) == 'b') seenB = true;
+            if (s.charAt(index) == 'a' && seenB) return false;
+        }
+        return true;
+    }
+}