23.02.28 学习

简单的树形DP，看代码即可

/**
 * 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:
    unordered_map<TreeNode*, unordered_map<int, int>> f;

    int rob(TreeNode* root) {
        if (!root) return 0;

        dfs(root);

        return max(f[root][0], f[root][1]);
    }

    void dfs(TreeNode* p) {
        if (!p) return ;

        dfs(p->left);
        dfs(p->right);
        f[p][0] = max(f[p->left][0], f[p->left][1]) + max(f[p->right][0], f[p->right][1]);
        f[p][1] = p->val + f[p->left][0] + f[p->right][0];
    }
};