• 删除节点没有左子树，直接返回右子树
    • 删除节点没有右子树，直接返回左子树
    • 两个都有，将删除节点的后继节点替换删除节点 ```java package com.alg.two;

    import com.alg.TreeNode;

    import java.util.Objects;

    /**

    • @author fuyao

    • @date 2022年06月02日 5:12 下午 */ public class DeleteTreeNode {

      public TreeNode deleteNode(TreeNode root, int key) {

      1.  if (Objects.isNull(root)){
      2.      return null;
      3.  }
      4.  if (root.val < key){
      5.      root.left = deleteNode(root.right,key);
      6.      return root;
      7.  }
      8.  if (root.val > key){
      9.      root.left = deleteNode(root.left,key);
      10.      return root;
      11.  }
      12.  if (root.val == key){
      13.      if (Objects.isNull(root.left) && Objects.isNull(root.right)){
      14.          return null;
      15.      }
      16.      if (Objects.isNull(root.left)){
      17.          return root.right;
      18.      }
      19.      if (Objects.isNull(root.right)){
      20.          return root.left;
      21.      }
      22.      TreeNode successor = root.right;
      23.      while (Objects.nonNull(successor.left)){
      24.          successor = successor.left;
      25.      }
      26.      root.right = deleteNode(successor.right,successor.val);
      27.      successor.left = root.left;
      28.      successor.right = root.right;
      29.      return successor;
      30.  }
      31.  return root;

      }

    }

    ```