| # | Title | Solutions | Video | Difficulty | Tag

|-----|----------------|---------------|--------|-------------|-------------

|2124|[Check if All A's Appears Before All B's](https://leetcode.com/problems/check-if-all-as-appears-before-all-bs/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2124.java)||Easy||

|2120|[Execution of All Suffix Instructions Staying in a Grid](https://leetcode.com/problems/execution-of-all-suffix-instructions-staying-in-a-grid/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2120.java)||Medium||

|2119|[A Number After a Double Reversal](https://leetcode.com/problems/a-number-after-a-double-reversal/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2119.java)||Easy||

|2116|[Check if a Parentheses String Can Be Valid](https://leetcode.com/problems/check-if-a-parentheses-string-can-be-valid/)|[Java](../master/src/main/java/com/fishercoder/solutions/_2116.java)||Medium||

packagecom.fishercoder.solutions;

publicclass_2124 {

publicstaticclassSolution1 {

publicbooleancheckString(Strings) {

intaIndex =s.lastIndexOf('a');

if (aIndex <0) {

returntrue;

}

for (inti =0;i <aIndex;i++) {

if (s.charAt(i) =='b') {

returnfalse;

}

}

returntrue;

}

}

}