地址:https://leetcode-cn.com/problems/binary-tree-inorder-traversal/
大意:给定一个二叉树,返回它的中序 遍历。
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int> inorderTraversal(TreeNode* root) {
stack<TreeNode*> stk;
vector<int> res;
TreeNode *kk = root;
while(stk.size() != 0 || kk != NULL){
if(kk != NULL){
stk.push(kk);
kk = kk->left;
}else{
kk = stk.top();
stk.pop();
res.push_back(kk->val);
kk = kk->right;
}
}
return res;
}
};