题目:
Given a non-empty binary tree, return the average value of the nodes on each level in the form of an array.
Example 1:
Input:
3
/ \
9 20
/ \
15 7
Output: [3, 14.5, 11]
Explanation:
The average value of nodes on level 0 is 3, on level 1 is 14.5, and on level 2 is 11. Hence return [3, 14.5, 11].
Note:
- The range of node's value is in the range of 32-bit signed integer.
代码:
使用队列的先进先出的特点:
class Solution {
public:
vector<double> averageOfLevels(TreeNode* root) {
vector<double> ret;
queue<TreeNode*> q;
q.push(root);
while (!q.empty()) {
long long t = 0;
int n = q.size();
for (int i = 0; i < n; i++) {
auto node = q.front();
q.pop();
if (node->left) q.push(node->left);
if (node->right) q.push(node->right);
t += node->val;
}
ret.push_back(double(t)/double(n));
}
return ret;
}
};