1 | Given a root node reference of a BST and a key, delete the node with the given key in the BST. Return the root node reference (possibly updated) of the BST. |
使用前序遍历的结构,如果当前节点即是删除节点,则分两种情况:
- 左右均非空,则把右子树的最小节点移动上来,并删除原节点
- 返回非空的那个节点
否则根据BST性质来选择性在某个子树中删除.1
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34/**
* 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 root;
if (root->val == key) {
if (root->left && root->right) {
TreeNode *p = root->right;
while (p->left) {
p = p->left;
}
root->val = p->val;
root->right = deleteNode(root->right, p->val);
return root;
}
return root->left ? root->left : root->right;
}
if (key < root->val) {
root->left = deleteNode(root->left, key);
return root;
}
root->right = deleteNode(root->right, key);
return root;
}
};