45 lines
1.3 KiB
Rust
45 lines
1.3 KiB
Rust
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//leetcode: https://leetcode.com/problems/binary-tree-preorder-traversal/
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use super::util::tree::{TreeNode, to_tree};
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// 前序遍历（Recursive Approach）
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pub fn preorder_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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_preorder(root, &mut result);
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result
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}
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fn _preorder(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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result.push(node.borrow().val);
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_preorder(node.borrow().left.clone(), result);
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_preorder(node.borrow().right.clone(), result);
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},
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None => { return; }
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}
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}
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// 前序遍历（Iterating method using Stack）
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pub fn inorder_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 stack: Vec<Rc<RefCell<TreeNode>>> = Vec::new();
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let mut r = root.clone();
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while r.is_some() || !stack.is_empty() {
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while let Some(node) = r {
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result.push(node.borrow().val);
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stack.push(node.clone());
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r = node.borrow().left.clone();
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}
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r = stack.pop();
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if let Some(node) = r {
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r = node.borrow().right.clone();
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}
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}
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result
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}
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