牛客网算法题JS（六）NC11 将升序数组转化为平衡二叉搜索树

解题一：二分+递归

/*
 * 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
    return dp(nums, 0, nums.length - 1);
}

function dp (num, left, right) {
        if (left > right) {
            return null;
        }
        let mid = (left + right + 1) / 2;
        root = new TreeNode(num[mid]);
        root.left = dp(num, left, mid - 1);
        root.right = dp(num, mid + 1, right);
        return root;
    }

module.exports = {
    sortedArrayToBST: sortedArrayToBST,
};