二叉树中序遍历 Q94 Binary Tree Inorder Traversal

三分钟写好快乐一下

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    ArrayList<Integer> ret = new ArrayList<Integer>();
    public List<Integer> inorderTraversal(TreeNode root) {
        Intrave(root);
        return ret;
        
    }
    void Intrave(TreeNode root){
        if(root == null)
            return;
        if(root.left != null)
        Intrave(root.left);
        ret.add(root.val);
        if(root.right != null)
        Intrave(root.right);
    }
}