65 lines
1.4 KiB
Rust
65 lines
1.4 KiB
Rust
/**
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* [144] Binary Tree Preorder Traversal
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*/
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pub struct Solution {}
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use crate::util::tree::{to_tree, TreeNode};
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// submission codes start here
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// Definition for a binary tree node.
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// #[derive(Debug, PartialEq, Eq)]
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// pub struct TreeNode {
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// pub val: i32,
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// pub left: Option<Rc<RefCell<TreeNode>>>,
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// pub right: Option<Rc<RefCell<TreeNode>>>,
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// }
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//
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// impl TreeNode {
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// #[inline]
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// pub fn new(val: i32) -> Self {
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// TreeNode {
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// val,
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// left: None,
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// right: None
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// }
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// }
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// }
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use std::cell::RefCell;
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use std::rc::Rc;
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impl Solution {
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pub fn preorder_traversal(root: Option<Rc<RefCell<TreeNode>>>) -> Vec<i32> {
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let mut result = Vec::new();
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let mut stack = Vec::new();
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let mut root = root;
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while root.is_some() || !stack.is_empty() {
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while let Some(r) = root {
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result.push(r.borrow().val);
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stack.push(Rc::clone(&r));
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root = r.borrow().left.clone();
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}
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let node = stack.pop().unwrap();
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root = node.borrow().right.clone();
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}
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result
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}
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}
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// submission codes end
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_144() {
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assert_eq!(
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Solution::preorder_traversal(to_tree(vec![Some(1), None, Some(2), Some(3)])),
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vec![1, 2, 3]
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);
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}
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}
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