update readme

Author: hogan-tech

.github/Question List.txt

@@ -4,5 +4,4 @@
 0004-median-of-two-sorted-arrays python hard
 0005-longest-palindromic-substring python medium
 
-2061-number-of-spaces-cleaning-robot-cleaned python medium
-2812-find-the-safest-path-in-a-grid python medium
+2331-evaluate-boolean-binary-tree python easy

README.md

@@ -459,6 +459,7 @@ The solutions are organized as follows:
 | 2251 | [Number of Flowers in Full Bloom](https://leetcode.com/problems/number-of-flowers-in-full-bloom/)                                                                   | [Python](./2251-number-of-flowers-in-full-bloom/2251-number-of-flowers-in-full-bloom.py)                                                                                                                                                                                       | [Hard](./2251-number-of-flowers-in-full-bloom/README.md)                                  |
 | 2264 | [Largest 3-Same-Digit Number in String](https://leetcode.com/problems/largest-3-same-digit-number-in-string/)                                                       | [Python](./2264-largest-3-same-digit-number-in-string/2264-largest-3-same-digit-number-in-string.py)                                                                                                                                                                           | [Easy](./2264-largest-3-same-digit-number-in-string/README.md)                            |
 | 2265 | [Count Nodes Equal to Average of Subtree](https://leetcode.com/problems/count-nodes-equal-to-average-of-subtree/)                                                   | [Python](./2265-count-nodes-equal-to-average-of-subtree/2265-count-nodes-equal-to-average-of-subtree.py)                                                                                                                                                                       | [Medium](./2265-count-nodes-equal-to-average-of-subtree/README.md)                        |
+| 2331 | [Evaluate Boolean Binary Tree](https://leetcode.com/problems/evaluate-boolean-binary-tree/)                                                                         | [Python](./2331-evaluate-boolean-binary-tree/2331-evaluate-boolean-binary-tree.py)                                                                                                                                                                                             | [Easy](./2331-evaluate-boolean-binary-tree/README.md)                                     |
 | 2353 | [Design a Food Rating System](https://leetcode.com/problems/design-a-food-rating-system/)                                                                           | [Python](./2353-design-a-food-rating-system/2353-design-a-food-rating-system.py)                                                                                                                                                                                               | [Medium](./2353-design-a-food-rating-system/README.md)                                    |
 | 2355 | [Maximum Number of Books You Can Take](https://leetcode.com/problems/maximum-number-of-books-you-can-take/)                                                         | [Python](./2355-maximum-number-of-books-you-can-take/2355-maximum-number-of-books-you-can-take.py)                                                                                                                                                                             | [Hard](./2355-maximum-number-of-books-you-can-take/README.md)                             |
 | 2361 | [Minimum Costs Using the Train Line](https://leetcode.com/problems/minimum-costs-using-the-train-line/)                                                             | [Python](./2361-minimum-costs-using-the-train-line/2361-minimum-costs-using-the-train-line.py)                                                                                                                                                                                 | [Hard](./2361-minimum-costs-using-the-train-line/README.md)                               |