二叉樹和最大的子樹__演算法

給一個二叉樹，每個節點都是正或負整數，如何找到一個子樹，它所有節點的和最大。

<pre name="code" class="cpp">struct Node{int val;Node *left;Node *right;};int visit(Node *root, int &result){if (root == NULL){return 0;}int sum = root->val;if (root->left != NULL || root->right != NULL){int left = visit(root->left, result);int right = visit(root->right, result);sum += left + right;result = max(sum, result);}return sum;}int maxSum(Node *root){int result = INT_MIN;visit(root, result);return result;}