450题

方法

class Solution {
public:
    int right_h(TreeNode* root){
        while(root->left){
            root=root->left;
        }
        return root->val;
    }
    int left_h(TreeNode* root){
        while(root->right){
            root=root->right;
        }
        return root->val;
    }
    TreeNode* deleteNode(TreeNode* root, int key) {
        if(root==nullptr){
            return root;
        }
        if(root->val>key){
            root->left=deleteNode(root->left,key);
        }
        else if(root->val<key){
            root->right=deleteNode(root->right,key);
        }else{
            if(!root->right&&!root->left){
                root=nullptr;
            }else if(root->right){
                int temp=right_h(root->right);
                root->val=temp;
                root->right=deleteNode(root->right,root->val);
            }else if(root->left){
                int temp=left_h(root->left);
                root->val=temp;
                root->left=deleteNode(root->left,root->val);
            }
        }
        return root;
    }
};