Validate Binary Search Tree [leetcode]

标签：leetcode

在递归函数中，加上max和min，保存当前子树的最大值和最小值

合法的二叉查找树：

1.左子树最大值<根节点

2.右子树最小值>根节点

3.子树均为合法的BST

bool isValidBST(TreeNode *root) {
        if (!root) return true;
        int max, min;
        return isValid(root, max, min);
    }
    
    bool isValid(TreeNode * root, int & max, int & min)
    {
        int subTreeMax, subTreeMin;
        max = min = root->val;
        if (root->left)
        {
            if (!isValid(root->left, subTreeMax, subTreeMin)) return false;
            if (subTreeMax >= root->val) return false;
            min = subTreeMin;
        }
        if (root->right)
        {
            if (!isValid(root->right, subTreeMax, subTreeMin)) return false;
            if (subTreeMin <= root->val) return false;
            max = subTreeMax;
        }
        return true;       
    }

Validate Binary Search Tree [leetcode]

标签：leetcode

原文地址：http://blog.csdn.net/peerlessbloom/article/details/39581083