leetcode_practice/binary_tree_level_order.cpp at master · daggarwa/leetcode_practice · GitHub

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/**
 * 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:
    vector<vector<int>> levelOrder(TreeNode* root) {


        vector<vector<int>> result;
        if (root==nullptr)
            return result;

        std::queue<TreeNode*> processq;

        processq.push(root);

        while(!processq.empty())
        {
            int queue_size = processq.size();
            vector<int> current_level_nodes;

            for(int i =0;i<queue_size;i++)
            {
                TreeNode* current_node = processq.front();
                processq.pop();
                if(current_node->left!=nullptr)
                {
                    processq.push(current_node->left);
                }
                if(current_node->right!=nullptr)
                {
                    processq.push(current_node->right);
                }

                current_level_nodes.push_back(current_node->val);

            }

            result.push_back(current_level_nodes);
        }

        return result;


    }
};