Convert sorted array to binary search tree

Array Divide and Conquer Tree Binary Search Tree Binary Tree

75.2% acceptance

Feb 27, 2026

11865

640

Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

// Definition for a binary tree node.
// #[derive(Debug, PartialEq, Eq)]
// pub struct TreeNode {
//   pub val: i32,
//   pub left: Option<Rc<RefCell<TreeNode>>>,
//   pub right: Option<Rc<RefCell<TreeNode>>>,
// }
// 
// impl TreeNode {
//   #[inline]
//   pub fn new(val: i32) -> Self {
//     TreeNode {
//       val,
//       left: None,
//       right: None
//     }
//   }
// }
use std::rc::Rc;
use std::cell::RefCell;
impl Solution {
  pub fn sorted_array_to_bst(nums: Vec<i32>) -> Option<Rc<RefCell<TreeNode>>> {
    fn build(nums: &[i32]) -> Option<Rc<RefCell<TreeNode>>> {
      if nums.is_empty() {
        return None;
      }
      
      let mid = nums.len() / 2;
      let left = build(&nums[..mid]);
      let right = build(&nums[mid + 1..]);
      
      Some(Rc::new(RefCell::new(TreeNode {
        val: nums[mid],
        left,
        right,
      })))
    }
    
    build(&nums)
  }
}