73 lines
1.5 KiB
Rust
73 lines
1.5 KiB
Rust
/**
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* [230] Kth Smallest Element in a BST
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*/
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pub struct Solution {}
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use crate::util::tree::{TreeNode, to_tree};
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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::rc::Rc;
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use std::cell::RefCell;
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impl Solution {
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fn inorder_iterate(node: &Rc<RefCell<TreeNode>>, count: &mut i32, target: i32) -> Option<i32> {
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if let Some(left) = node.borrow().left.as_ref() {
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if let Some(result) = Self::inorder_iterate(left, count, target) {
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return Some(result);
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}
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};
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*count += 1;
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if *count == target {
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return Some(node.borrow().val);
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}
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if let Some(right) = node.borrow().right.as_ref() {
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if let Some(result) = Self::inorder_iterate(right, count, target) {
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return Some(result);
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}
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}
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None
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}
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pub fn kth_smallest(root: Option<Rc<RefCell<TreeNode>>>, k: i32) -> i32 {
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let mut count = 0;
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if let Some(root) = root {
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return Self::inorder_iterate(&root, &mut count, k).unwrap()
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}
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0
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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_230() {
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}
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}
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