二叉树任务调度

/*
 * 思路：
 * 1. 使用Java Stream API处理树的遍历和计算。
 * 2. 递归地处理每个节点，计算其最小执行时间。
 */

import java.util.*;

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode(int x) { val = x; }
}

public class Solution {
    public double minimalExecTime(TreeNode root) {
        return helper(root).findFirst().get()[0];
    }

    private Stream<double[]> helper(TreeNode root) {
        if (root == null) {
            return Stream.of(new double[] {0, 0});
        }

        double[] left = helper(root.left).findFirst().get();
        double[] right = helper(root.right).findFirst().get();

        double leftTime = left[0], rightTime = right[0];
        double leftRemain = left[1], rightRemain = right[1];

        double total = Math.max(leftTime, rightTime);
        double remaining = root.val + Math.min(leftRemain, rightRemain);

        return Stream.of(new double[] {total + root.val, remaining});
    }
}