337. 打家劫舍 III

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C代码：二叉树 + 动态规划

typedef struct  {  // 每个节点都有两个状态：选中、不选中int selected;int notSelected;
} SubtreeStatus;SubtreeStatus dfs(struct TreeNode *node) {if (!node) {return (SubtreeStatus){0, 0};}SubtreeStatus l = dfs(node->left);SubtreeStatus r = dfs(node->right);int selected = node->val + l.notSelected + r.notSelected;  // 后序遍历，如果选中父节点，则子节点没有选中// 父节点没有选中，则子节点可选中、可不选中；往上迭代！int notSelected = fmax(l.selected, l.notSelected) + fmax(r.selected, r.notSelected);return (SubtreeStatus){selected, notSelected};
}int rob(struct TreeNode *root) {SubtreeStatus rootStatus = dfs(root);return fmax(rootStatus.selected, rootStatus.notSelected);
}