题解 | 将升序数组转化为平衡二叉搜索树

/*
 * function TreeNode(x) {
 *   this.val = x;
 *   this.left = null;
 *   this.right = null;
 * }
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param nums int整型一维数组 
 * @return TreeNode类
 */
function sortedArrayToBST(nums) {
  // write code here
  if(!nums?.length) return null;
  if (nums.length === 1) return new TreeNode(nums[0]);
  // find the root, in middle
  const rootIndex = Math.floor(nums.length / 2);
  const root = new TreeNode(nums[rootIndex]);


  // find the next root in the subtree
  if (rootIndex - 1 >= 0)
    root.left = sortedArrayToBST(nums.slice(0, rootIndex));
  if (rootIndex + 1 <= nums.length - 1)
    root.right = sortedArrayToBST(nums.slice(rootIndex+1));
  

  return root;
}
module.exports = {
    sortedArrayToBST : sortedArrayToBST
};