450.删除二叉搜索树中的节点.java

/*
 * @lc app=leetcode.cn id=450 lang=java
 *
 * [450] 删除二叉搜索树中的节点
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public TreeNode deleteNode(TreeNode root, int key) {
        if(root==null)return null;
        if(root.val==key){
          if(root.left==null)return root.right;
          if(root.right==null)return root.left;
          TreeNode minNode=getMin(root.right);
          root.val=minNode.val;
          root.right=deleteNode(root.right,minNode.val);
        }
        else if(root.val>key){
root.left=deleteNode(root.left, key);
        }else if(root.val<key){
root.right=deleteNode(root.right,key);
        }
        return root;
    }
    public TreeNode getMin(TreeNode node){
      while(node.left!=null){
        node=node.left;
      }
      return node;
    }
}
// @lc code=end