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程式語言 - LeetCode - C++ - 337. House Robber III

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題目：


方法：

偷當前節點：node->val + left[0] + right[0]
不偷當前節點：max(left) + max(right)

解答：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    int rob(TreeNode* root) {
        auto dfs = [&](this auto& dfs, TreeNode *n) -> pair<int, int> {
            if (!n) {
                return { 0, 0 };
            }

            auto l = dfs(n->left);
            auto r = dfs(n->right);

            int rob = n->val + l.first + r.first;
            int not_rob = max(l.first, l.second) + max(r.first, r.second);

            return { not_rob, rob };
        };

        auto ans = dfs(root);
        return max(ans.first, ans.second);
    }
};