LeetCodeAnimation/0094-Binary-Tree-Inorder-Traversal/cpp-0094/main4.cpp

/// Source : https://leetcode.com/problems/binary-tree-inorder-traversal/
/// Author : liuyubobobo
/// Time   : 2017-05-30

#include <iostream>
#include <vector>
#include <stack>

using namespace std;


/// Definition for a binary tree node.
struct TreeNode {
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};


// Another Classic Non-Recursive algorithm for inorder traversal
// Time Complexity: O(n), n is the node number in the tree
// Space Complexity: O(h), h is the height of the tree
class Solution {

public:
    vector<int> inorderTraversal(TreeNode* root) {

        vector<int> res;
        if( root == NULL )
            return res;

        stack<TreeNode*> stack;
        TreeNode* cur = root;
        while(cur != NULL || !stack.empty()){

            if(cur != NULL){
                stack.push(cur);
                cur = cur->left;
            }
            else {
                cur = stack.top();
                stack.pop();
                res.push_back(cur->val);
                cur = cur->right;
            }
        }
        return res;
    }
};

int main() {

    return 0;
}