*二叉树*非迭代中序遍历

题目详情

/**
 * struct TreeNode {
 *    int val;
 *    struct TreeNode *left;
 *    struct TreeNode *right;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param root TreeNode类 
     * @return int整型vector
     */
    vector<int> inorderTraversal(TreeNode* root) {
        // write code here
        vector<int> res;
        if(!root) return res;
        stack<TreeNode*> st;
        TreeNode *p = root;
        while(!st.empty()||p)
        {
            while(p)
            {
                st.push(p);
                p=p->left;
            }
            if(!st.empty())
            {
                TreeNode *node = st.top();
                st.pop();
                res.push_back(node->val);
                p=node->right;
            }
        }
        return res;


    }
};