654. 最大二叉树

题解

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {number[]} nums
 * @return {TreeNode}
 */
var constructMaximumBinaryTree = function (nums) {
    return build(nums, 0, nums.length - 1);
};
const build = (nums, low, high) => {
    let idx = 0;
    let maxValue = Number.MIN_SAFE_INTEGER;
    for (let i = low; i <=high; i++) {
        let num = nums[i];
        if (num > maxValue) {
            maxValue = num;
            idx = i;
        }
    }
    if (low > high) return null;
    let newNode = new TreeNode(maxValue);
    newNode.left = build(nums, low, idx-1);
    newNode.right = build(nums, idx + 1, high);
    return newNode;
}