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程式語言 - LeetCode - CPP - 637. Average of Levels in Binary Tree

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題目：


解答：

/**
 * 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) {
        queue<TreeNode*> q;
        vector<double> ans;

        q.push(root);
        
        while (!q.empty()) {
            double v = 0;
            int size = q.size();

            for (int i = 0; i < size; ++i) {
                TreeNode* r = q.front();

                q.pop();
                v += r->val;

                if (r->right) {
                    q.push(r->right);
                }
                if (r->left) {
                    q.push(r->left);
                }
            }

            ans.push_back(v / size);
        }

        return ans;
    }
};