700. Search in a Binary Search Tree

You are given the root of a binary search tree (BST) and an integer val.

Find the node in the BST that the node's value equals val and return the subtree rooted with that node. If such a node does not exist, return null.

 

Example 1:

Input: root = [4,2,7,1,3], val = 2
Output: [2,1,3]

Example 2:

Input: root = [4,2,7,1,3], val = 5
Output: []

 

Constraints:

  • The number of nodes in the tree is in the range [1, 5000].
  • 1 <= Node.val <= 107
  • root is a binary search tree.
  • 1 <= val <= 107

Rust Solution

struct Solution;
use rustgym_util::*;

trait Search {
    fn find(&self, val: i32) -> TreeLink;
}

impl Search for TreeLink {
    fn find(&self, val: i32) -> TreeLink {
        if let Some(node) = self {
            let temp = node.clone();
            let node = node.borrow();
            if val == node.val {
                Some(temp)
            } else {
                if val < node.val {
                    Self::find(&node.left, val)
                } else {
                    Self::find(&node.right, val)
                }
            }
        } else {
            None
        }
    }
}

impl Solution {
    fn search_bst(root: TreeLink, val: i32) -> TreeLink {
        root.find(val)
    }
}

#[test]
fn test() {
    let root = tree!(4, tree!(2, tree!(1), tree!(3)), tree!(3));
    let res = tree!(2, tree!(1), tree!(3));
    assert_eq!(Solution::search_bst(root, 2), res);
}

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