Add enum based rust solution for binarytrees

bench/algorithm/binarytrees/6.rs

@@ -0,0 +1,53 @@
+use std::cmp::max;
+
+enum TreeNode {
+    Leaf,
+    Node(Box<TreeNode>, Box<TreeNode>),
+}
+
+impl TreeNode {
+    fn check(&self) -> usize {
+        match &self {
+            TreeNode::Leaf => 1,
+            TreeNode::Node(left, right) => 1 + left.check() + right.check(),
+        }
+    }
+
+    fn create(depth: usize) -> Box<TreeNode> {
+        if depth > 0 {
+            let next_depth = depth - 1;
+            Box::new(TreeNode::Node(Self::create(next_depth), Self::create(next_depth)))
+        } else {
+            Box::new(TreeNode::Leaf)
+        }
+    }
+}
+
+const MIN_DEPTH: usize = 4;
+
+fn main() {
+    let n = std::env::args_os()
+        .nth(1)
+        .and_then(|s| s.into_string().ok())
+        .and_then(|n| n.parse().ok())
+        .unwrap_or(10);
+
+    let max_depth = max(MIN_DEPTH + 2, n);
+    let stretch_depth = max_depth + 1;
+
+    println!("stretch tree of depth {}\t check: {}", stretch_depth, TreeNode::create(stretch_depth).check());
+
+    let long_lived_tree = TreeNode::create(max_depth);
+
+    for iteration_depth in (MIN_DEPTH..stretch_depth).step_by(2) {
+        let iterations = 1 << (max_depth - iteration_depth + MIN_DEPTH);
+        let mut nodes = 0;
+        for _ in 0..iterations {
+            nodes += TreeNode::create(iteration_depth).check();
+        }
+        println!("{iterations}\t trees of depth {iteration_depth}\t check: {nodes}")
+    }
+
+    let nodes = long_lived_tree.check();
+    println!("long lived tree of depth {max_depth}\t check: {nodes}");
+}