🌗 337. 打家劫舍 III

难度: 🌗

问题描述

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解法

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public int rob(TreeNode root) {
        // 思路：
        // 二叉树的后序遍历 + dp
        int[] res = mySol(root);
        return Math.max(res[0], res[1]);
    }

    private int[] mySol(TreeNode root) {
        int[] res = new int[] {0, 0};
        // 递归终止条件
        if(root == null) {
            return res;
        }
        
        int[] left = mySol(root.left);
        int[] right = mySol(root.right);

        // 单层递归逻辑
        res[0] = Math.max(left[0], left[1]) + Math.max(right[0], right[1]);
        res[1] = left[0] + right[0] + root.val;
        return res;
    }
}

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输出