20240221 Finsihed
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@ -50,4 +50,5 @@ mod p987_vertical_order_traversal_of_a_binary_tree;
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mod p102_binary_tree_level_order_traversal;
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mod p107_binary_tree_level_order_traversal_ii;
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mod p103_binary_tree_zigzag_level_order_traversal;
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mod p105_construct_binary_tree_from_preorder_and_inorder_traversal;
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mod p105_construct_binary_tree_from_preorder_and_inorder_traversal;
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mod p106_construct_binary_tree_from_inorder_and_postorder_traversal;
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@ -0,0 +1,98 @@
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/**
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* [106] Construct Binary Tree from Inorder and Postorder 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 build_tree(inorder: Vec<i32>, postorder: Vec<i32>) -> Option<Rc<RefCell<TreeNode>>> {
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if inorder.len() == 0 {
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return None;
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}
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let root = Rc::new(RefCell::new(TreeNode::new(postorder[postorder.len() - 1])));
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let mut stack = Vec::new();
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stack.push(Rc::clone(&root));
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let mut inorder_index = inorder.len() - 1;
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for i in (0..postorder.len() - 1).rev() {
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let post_order_value = postorder[i];
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let mut node = Rc::clone(stack.last().unwrap());
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if node.borrow().val != inorder[inorder_index] {
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let new_node = Rc::new(RefCell::new(TreeNode::new(post_order_value)));
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stack.push(Rc::clone(&new_node));
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node.borrow_mut().right = Some(new_node);
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} else {
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while let Some(top) = stack.last() {
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if top.borrow().val == inorder[inorder_index] {
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node = Rc::clone(top);
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stack.pop();
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inorder_index -= 1;
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} else {
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break;
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}
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}
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let new_node = Rc::new(RefCell::new(TreeNode::new(post_order_value)));
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stack.push(Rc::clone(&new_node));
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node.borrow_mut().left = Some(new_node);
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}
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}
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Some(root)
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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_106() {
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assert_eq!(
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Solution::build_tree(vec![9, 3, 15, 20, 7], vec![9, 15, 7, 20, 3]),
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to_tree(vec![
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Some(3),
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Some(9),
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Some(20),
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None,
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None,
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Some(15),
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Some(7)
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])
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);
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assert_eq!(
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Solution::build_tree(vec![-1], vec![-1]),
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to_tree(vec![Some(-1)])
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);
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}
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}
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