我用java写的一直报内部错误

Question

public class Solution {
    public List<Integer> preorderTraversal(TreeNode root) {
        List<Integer> ret = new LinkedList<>();
        if(root == null)
            return ret;
        Stack<Command> stack = new Stack<>();
        stack.push(Command("go",root));
        while(!stack.isEmpty()){
            Command temp = stack.pop();
            if(temp.res == "to"){
                ret.add(temp.node.val);
            }else{
                if(temp.node.right != null)
                    stack.push(Command("go",temp.node.right));
                if(temp.node.left != null)
                    stack.push(Command("go",temp.node.left));
                stack.push(Command("to",temp.node));
            }
        }
        return ret;
    }

}

Answer 1

liuyubobobo 2018-08-24 17:34:28

可以参考课程官方github中提供的源码参考。本小节Java源码传送门：https://github.com/liuyubobobo/Play-with-Algorithm-Interview/tree/master/06-Stack-and-Queue/Course%20Code%20(Java)/03-Non-Recursive-Implementation-of-a-Recursive-Algorithm/src

加油！：）