problems(rs): add „94. Binary Tree Inorder Traversal“

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/binary-tree-inorder-traversal.rs

@@ -0,0 +1,40 @@
+// Definition for a binary tree node.
+// #[derive(Debug, PartialEq, Eq)]
+// pub struct TreeNode {
+//   pub val: i32,
+//   pub left: Option<Rc<RefCell<TreeNode>>>,
+//   pub right: Option<Rc<RefCell<TreeNode>>>,
+// }
+//
+// impl TreeNode {
+//   #[inline]
+//   pub fn new(val: i32) -> Self {
+//     TreeNode {
+//       val,
+//       left: None,
+//       right: None
+//     }
+//   }
+// }
+use std::rc::Rc;
+use std::cell::RefCell;
+impl Solution {
+    fn inorder(values: &mut Vec<i32>, node: Option<&Rc<RefCell<TreeNode>>>) {
+        match node {
+            None => {},
+            Some(n) => {
+                Solution::inorder(values, (*n).borrow().left.as_ref());
+                values.push((*n).borrow().val);
+                Solution::inorder(values, (*n).borrow().right.as_ref());
+            }
+        }
+    }
+
+    pub fn inorder_traversal(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
+        let mut values: Vec<i32> = Vec::new();
+
+        Solution::inorder(&mut values, root.as_ref());
+
+        values
+    }
+}