java: add «2331. Evaluate Boolean Binary Tree»

Signed-off-by: Matej Focko <me@mfocko.xyz>

java/evaluate-boolean-binary-tree.java

@@ -0,0 +1,33 @@
+public class TreeNode {
+  int val;
+  TreeNode left;
+  TreeNode right;
+
+  TreeNode() {}
+
+  TreeNode(int val) {
+    this.val = val;
+  }
+
+  TreeNode(int val, TreeNode left, TreeNode right) {
+    this.val = val;
+    this.left = left;
+    this.right = right;
+  }
+}
+
+class Solution {
+  public boolean evaluateTree(TreeNode node) {
+    if (node == null) {
+      throw new NullPointerException("node cannot be null");
+    }
+
+    return switch (node.val) {
+      case 0 -> false;
+      case 1 -> true;
+      case 2 -> evaluateTree(node.left) || evaluateTree(node.right);
+      case 3 -> evaluateTree(node.left) && evaluateTree(node.right);
+      default -> throw new IllegalStateException("value must be in range ⟨0;3⟩");
+    };
+  }
+}