面试必考精华版Leetcode最大层内元素和

题目：

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代码（首刷看解析）：

class Solution {
public:
    int maxLevelSum(TreeNode* root) {
        int ans =1,maxSum=root->val;
        vector q = {root};
        for(int level = 1;!q.empty();++level){
            vector nq;
            int sum=0;
            for(auto node:q){
                sum+=node->val;
                if(node->left) nq.push_back(node->left);
                if(node->right) nq.push_back(node->right);
            }
            if(sum>maxSum){
                maxSum=sum;
                ans=level;
            }
            q=move(nq);
        }
        return ans;
    }
};