2021-11-26 700二叉搜索树

送分题，二叉树遍历就行了，至于怎么遍历都行。用的常规思路做的。

Go版本：

 var res *TreeNode; 
func searchBST(root *TreeNode, val int) *TreeNode {
res=nil;
return dfs(root,val);
}
func dfs(root *TreeNode,val int)*TreeNode{
if(root==nil){
    return nil;
}
if root.Val==val{
res=root;
}
dfs(root.Left,val);
dfs(root.Right,val);
return res;
}

java版本：

/**
 * 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 {
    TreeNode res;
    public TreeNode searchBST(TreeNode root, int val) {

       return dfs(root,val);

    }
    public TreeNode dfs(TreeNode root,int val){

        if(root==null){
            return null;
        }
        if(root.val==val){
            res=root;
        }
        dfs(root.left,val);
        dfs(root.right,val);
        return res;
    }
}