49 lines
1.4 KiB
Rust
49 lines
1.4 KiB
Rust
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// https://leetcode.com/problems/binary-tree-postorder-traversal/
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use super::util::tree::{TreeNode, to_tree};
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// 后续遍历（Recursive Approach）
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pub fn postorder_traversal(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
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let mut result: Vec<i32> = vec![];
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if root.is_none() { return result; }
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_postorder(root, &mut result);
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result
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}
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fn _postorder(root: Option<Rc<RefCell<TreeNode>>>, result: &mut Vec<i32>) {
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match root {
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Some(node) => {
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_postorder(node.borrow().left.clone(), result);
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_postorder(node.borrow().right.clone(), result);
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result.push(node.borrow().val);
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},
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None => { return; }
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}
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}
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// 后序遍历（Iterating method using Stack）
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pub fn postorder_traversal(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
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let mut result = vec![];
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if root.is_none() { return result; }
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let mut stack1: Vec<Option<Rc<RefCell<TreeNode>>>> = Vec::new();
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let mut stack2: Vec<Option<Rc<RefCell<TreeNode>>>> = Vec::new();
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stack1.push(root);
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while let Some(Some(node)) = stack1.pop() {
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if node.borrow().left.is_some() {
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stack1.push(node.borrow().left.clone());
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}
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if node.borrow().right.is_some() {
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stack1.push(node.borrow().right.clone());
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}
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stack2.push(Some(node));
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}
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while let Some(Some(node)) = stack2.pop() {
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result.push(node.borrow().val);
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}
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result
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}
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