Solved 0145

Author: guangsheng.li01

src/a0145_binary_tree_postorder_traversal.rs

@@ -0,0 +1,74 @@
+/*
+ * [0145] binary-tree-postorder-traversal
+ */
+
+pub struct Solution {}
+use super::utils::tree::TreeNode;
+
+// solution impl starts here
+
+// 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::cell::RefCell;
+use std::rc::Rc;
+impl Solution {
+    pub fn postorder_traversal(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
+        let mut res: Vec<i32> = Vec::new();
+        Solution::travel(&root, &mut res);
+        res
+    }
+
+    pub fn travel(root: &Option<Rc<RefCell<TreeNode>>>, v: &mut Vec<i32>) {
+        if root.is_none() {
+            return;
+        }
+
+        if let Some(r) = root {
+            let b = r.borrow();
+            if !b.left.is_none() {
+                Solution::travel(&b.left, v);
+            }
+
+            if !b.right.is_none() {
+                Solution::travel(&b.right, v);
+            }
+
+            v.push(b.val);
+        }
+    }
+}
+
+// solution impl ends here
+
+// solution tests starts here
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_case0() {
+        assert_eq!(
+            Solution::postorder_traversal(tree![1, null, 2, 3]),
+            vec![3, 2, 1]
+        );
+    }
+}
+
+// solution tests ends here

src/lib.rs

@@ -7,6 +7,7 @@ mod a0000_sample;
 mod a0001_two_sum;
 mod a0007_reverse_integer;
 mod a0009_palindrome_number;
+mod a0145_binary_tree_postorder_traversal;
 mod a0172_factorial_trailing_zeroes;
 mod a0400_nth_digit;
 mod a0404_sum_of_left_leaves;