Leetcode•Sep 29, 2025
House Robber III
Hazrat Ali
Leetcode
Besides the root, each house has one and only one parent house. After a tour, the smart thief realized that all houses in this place form a binary tree. It will automatically contact the police if two directly-linked houses were broken into on the same night.
Given the root of the binary tree, return the maximum amount of money the thief can rob without alerting the police.
Example 1:
Input: root = [3,2,3,null,3,null,1] Output: 7 Explanation: Maximum amount of money the thief can rob = 3 + 3 + 1 = 7.
Example 2:
Input: root = [3,4,5,1,3,null,1] Output: 9 Explanation: Maximum amount of money the thief can rob = 4 + 5 = 9.
Solution
/**
*
* @param {TreeNode} root
* @return {number}
*/
const robR = root => {
if (!root) {
return 0;
}
let val = 0;
if (root.left) {
val += robR(root.left.left) + robR(root.left.right);
}
if (root.right) {
val += robR(root.right.left) + robR(root.right.right);
}
return Math.max(val + root.val, robR(root.left) + robR(root.right));
};
const rob = root => {
const res = robSub(root);
return Math.max(res[0], res[1]);
};
const robSub = root => {
if (root == null) {
return [0, 0];
}
const left = robSub(root.left);
const right = robSub(root.right);
const res = [0, 0];
res[0] = Math.max(left[0], left[1]) + Math.max(right[0], right[1]);
res[1] = root.val + left[0] + right[0];
return res;
};