637. 二叉树的层平均值

C++

方法类似于进行二叉树的层遍历

/**
 * 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<double> averageOfLevels(TreeNode* root) {
        vector<double> ret;
        queue<TreeNode *> q;
        q.push(root);
        while(!q.empty())
        {
            int size = q.size();
            double currentSum = 0;
            for(int i = 0; i < size; i++)
            {
                TreeNode* node = q.front();
                currentSum += node->val;
                q.pop();
                if(node->left)  q.push(node->left);
                if(node->right) q.push(node->right);
            }
            ret.push_back(currentSum/size);
        }
        return ret;
    }
};