Leetcode 637. 二叉树的层平均值

层序遍历

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    vector<double> averageOfLevels(TreeNode* root) {
        layerorder(root);
        return average();
    }
private:
    struct node{
        double total = 0;
        int count = 0;
    };
    vector<node> layer;
    void layerorder(TreeNode* root){
        queue<TreeNode*> q;
        queue<int> lay;
        if(root==NULL) return;
        q.push(root);
        lay.push(0);
        while(q.empty()==false){
            TreeNode* front  = q.front();
            q.pop();
            int level = lay.front();
            lay.pop();
            if(front->left!=NULL){
                q.push(front->left);
                lay.push(level+1);
            }
            if(front->right!=NULL){
                q.push(front->right);
                lay.push(level+1);
            }
            if(layer.size()<level+1){
                node a = node();
                layer.push_back(a);
            }
            layer[level].total +=front->val;
            layer[level].count +=1;
        }
        return;
    }

    vector<double> average(){
        vector<double> aver;
        for(int i = 0;i<layer.size();i++){
            aver.push_back(layer[i].total/layer[i].count);
        }
        return aver;
    }
};