Added Average of Levels in Binary Tree

Author: ryanoneill

src/average_of_levels_in_binary_tree.rs

@@ -0,0 +1,70 @@
+use crate::tree_node::TreeNode;
+use crate::tree_node_additions::TreeNodeAdditions;
+use std::cell::RefCell;
+use std::collections::VecDeque;
+use std::rc::Rc;
+
+/// Given the `root` of a binary tree, return the average value of the nodes
+/// on each level in the form of an array. Answers within `10^-5` of the actual
+/// answer will be accepted.
+struct Solution;
+
+impl Solution {
+
+    pub fn average_of_levels(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<f64> {
+        let mut result = Vec::new();
+        let mut queue = VecDeque::new();
+
+        queue.push_back(root.clone());
+        while !queue.is_empty() {
+            let n = queue.len();
+            let mut sum = 0.0;
+            for _ in 0..n {
+                let item = queue.pop_front().unwrap();
+                match item {
+                    Some(rc) => {
+                        let node = rc.borrow();
+                        sum += node.val as f64;
+                        if node.left.is_some() {
+                            queue.push_back(node.left.clone());
+                        }
+                        if node.right.is_some() {
+                            queue.push_back(node.right.clone());
+                        }
+                    }
+                    None => { }
+                }
+            }
+            let average = sum / n as f64;
+            result.push(average);
+        }
+
+        result
+    }
+
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::serialize_and_deserialize_binary_tree::Codec;
+    use super::Solution;
+
+    #[test]
+    fn example_1() {
+        let data = "[3,9,20,null,null,15,7]".to_string();
+        let codec = Codec::new();
+        let root = codec.deserialize(data);
+        let result = Solution::average_of_levels(root);
+        assert_eq!(result, vec![3.00000,14.50000,11.00000]);
+    }
+
+    #[test]
+    fn example_2() {
+        let data = "[3,9,20,15,7]".to_string();
+        let codec = Codec::new();
+        let root = codec.deserialize(data);
+        let result = Solution::average_of_levels(root);
+        assert_eq!(result, vec![3.00000,14.50000,11.00000]);
+    }
+
+}

src/lib.rs

@@ -157,6 +157,8 @@ pub mod number_of_provinces; // 547
 
 pub mod reverse_words_in_a_string_iii; // 557
 
+pub mod average_of_levels_in_binary_tree; // 637
+
 pub mod find_k_closest_elements; // 658
 
 pub mod top_k_frequent_words; // 692