450 Delete Node in a BST 删除二叉搜索树中的结点

详见：https://leetcode.com/problems/delete-node-in-a-bst/description/

C++：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* deleteNode(TreeNode* root, int key)
    {
        if (!root)
        {
            return nullptr;
        }
        if (root->val > key)
        {
            root->left = deleteNode(root->left, key);
        }
        else if (root->val < key)
        {
            root->right = deleteNode(root->right, key);
        }
        else
        {
            if (!root->left || !root->right)
            {
                root = (root->left) ? root->left : root->right;
            }
            else
            {
                TreeNode *cur = root->right;
                while (cur->left)
                {
                    cur = cur->left;
                }
                root->val = cur->val;
                root->right = deleteNode(root->right, cur->val);
            }
        }
        return root;
    }
};

参考：https://www.cnblogs.com/grandyang/p/6228252.html