by level order
Intuition\n Describe your first thoughts on how to solve this problem. \n\n# Approach\n Describe your approach to solving the problem. \n\n# Complexity\n- Time 
# Intuition\n<!-- Describe your first thoughts on how to solve this problem. -->\n\n# Approach\n<!-- Describe your approach to solving the problem. -->\n\n# Complexity\n- Time complexity:\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity:\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\n/**\n * Definition for a binary tree node.\n * struct TreeNode {\n *     int val;\n *     TreeNode *left;\n *     TreeNode *right;\n *     TreeNode() : val(0), left(nullptr), right(nullptr) {}\n *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}\n *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}\n * };\n */\nclass Solution {\npublic:\n    int findBottomLeftValue(TreeNode* root) {\n        queue<TreeNode*>q;\n        q.push(root);\n        int num=0;\n        while(!q.empty()){\n            int n=q.size();\n            for(int i=0; i<n; i++){\n                TreeNode* temp=q.front();\n                q.pop();\n                if(i==0) num=temp->val;\n                if(temp->left) q.push(temp->left);\n                if(temp->right) q.push(temp->right);\n            }\n        }\n        return num;\n    }\n};\n```
['Queue', 'C++']