Binary Tree Inorder Traversal @leetcode

http://oj.leetcode.com/problems/binary-tree-inorder-traversal/

vector<int> inorderTraversal(TreeNode *root) {
        stack<TreeNode *> nextstep;
        vector<int> res;
        TreeNode *p=root;
        TreeNode *DIRTY = new TreeNode(0);
        bool isMid = true;
        while(p){
            if(p->right && isMid) {nextstep.push(p->right);}
            
            if(p == DIRTY){
                p = nextstep.top();
                isMid = (p == DIRTY)?false:true;
                nextstep.pop();
            }
            if(p->left && isMid){
                nextstep.push(p);
                nextstep.push(DIRTY);
                p = p->left;
            }
            else{
                if(p)
                    res.push_back(p->val);
                if(nextstep.size()>0){
                    p = nextstep.top();
                    isMid = (p == DIRTY)?false:true;
                    nextstep.pop();
                    if(!isMid){
                        p = nextstep.top();
                        nextstep.pop();
                    }
                }
                else{
                    break;
                }
            }
        }
        delete DIRTY;
        return res;
    }

=发现二叉树跟栈，队列这些数据结构的东西，真是可以完美结合。

#相信还有更好的办法，也许我下次再写这道题，就会更好。