<p>Given the <code>root</code> of a binary tree, return <em>all root-to-leaf paths in <strong>any order</strong></em>.</p>

<p>A <strong>leaf</strong> is a node with no children.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/03/12/paths-tree.jpg" style="width: 207px; height: 293px;" />
<pre>
<strong>Input:</strong> root = [1,2,3,null,5]
<strong>Output:</strong> [&quot;1-&gt;2-&gt;5&quot;,&quot;1-&gt;3&quot;]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> root = [1]
<strong>Output:</strong> [&quot;1&quot;]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the tree is in the range <code>[1, 100]</code>.</li>
	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
</ul>

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    void helper(TreeNode* root, vector<string>&ans, string& temp){
        if(root==NULL) return ;

        if(root->left ==NULL && root->right==NULL){
            temp+= to_string(root->val);
            ans.push_back(temp);
            return ;
        }
        temp += to_string(root->val);
        temp+= "->";
        string temp2 = temp;
        helper(root->left, ans, temp);
        temp = temp2;
        helper(root->right, ans, temp);
    }
    vector<string> binaryTreePaths(TreeNode* root) {
        // Recursion
        // vector<string> ans;
        // string temp = "";
        // helper(root,ans, temp);
        // return ans;

        // By Iteration
        vector<string> ans;
        stack<pair<TreeNode*, string>> st;
        st.push({root, to_string(root->val)});

        while(st.empty()!=1){
            auto [node, curr_path] = st.top();
            st.pop();

            if(node->left==NULL && node->right==NULL){
                ans.push_back(curr_path);
            }

            if(node->left) st.push({node->left, curr_path+ "->"+to_string(node->left->val)});
            if(node->right) st.push({node->right, curr_path+ "->"+ to_string(node->right->val)});
        }

        return ans;
    }
};
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