C++ iterative solution with stack of pairs


  • 0
    M
    /**
     * 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<string> binaryTreePaths(TreeNode* root) {
        vector<string> ret_vec;
        if(root == NULL){
            return ret_vec;
        }
        
        TreeNode* pt = root;
        stack<pair<TreeNode*, string>> tree_stack;
        tree_stack.push(pair<TreeNode*, string>(pt, to_string(pt->val)));
        
        while(!tree_stack.empty()){
            
            pt = (tree_stack.top().first);
            string temp = tree_stack.top().second;
            tree_stack.pop();
            if(pt->right != NULL){
                tree_stack.push(pair<TreeNode*, string>(pt->right, temp + "->" + to_string(pt->right->val)));
            }
            if(pt->left != NULL){
                tree_stack.push(pair<TreeNode*, string>(pt->left, temp + "->" + to_string(pt->left->val)));
            }
            if(pt->left == NULL && pt->right == NULL){
                ret_vec.push_back(temp);
            }
        }
        
        return ret_vec;
        }
    };
    

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