Game of 24 Solver - Best in Class

[master]

Dear All -

We have just created a new Game of 24 Solver that would provide complete set of ALL solutions. Please check out and leave your feedback (missing solutions, solution errors are welcome!). As a fun scavenger hunt play, please list the four numbers that has one and only one solutions. For example, I found the following two sets (the Random button will be handy!):

1 5 8 13
2 3 8 13

Some hard sets:

3 7 9 13
2 5 5 10
1 3 4 6
1 6 11 13
3 6 6 11
3 3 7 7
2 3 5 12

Enjoy!