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102. Binary Tree Level Order Traversal

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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>> res;
        if(!root) return res;
        res.resize(2000);
        queue<tuple<TreeNode*,int>> Q;
        Q.push(make_tuple(root,0));
        tuple<TreeNode*,int> temp;
        int maxlevel = 0;
        while(!Q.empty()){
            temp = Q.front();
            res[get<1>(temp)].push_back(get<0>(temp)->val);
            if(get<1>(temp) > maxlevel) maxlevel = get<1>(temp);
            Q.pop();
            if(get<0>(temp)->left)
                Q.push(make_tuple(get<0>(temp)->left,get<1>(temp)+1));
            if(get<0>(temp)->right)
                Q.push(make_tuple(get<0>(temp)->right,get<1>(temp)+1));
        }
        res.resize(maxlevel+1);
        return res;
    }
};