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feat: add solutions to lc problem: No.0637. Average of Levels in Binary Tree
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-19
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‎solution/0600-0699/0637.Average of Levels in Binary Tree/README.md

+59-2
Original file line numberDiff line numberDiff line change
@@ -43,15 +43,72 @@
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
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# self.val = val
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# self.left = left
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# self.right = right
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class Solution:
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def averageOfLevels(self, root: TreeNode) -> List[float]:
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res = []
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q = collections.deque([root])
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while q:
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n = len(q)
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s = 0
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for _ in range(n):
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node = q.popleft()
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s += node.val
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if node.left:
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q.append(node.left)
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if node.right:
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q.append(node.right)
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res.append(s / n)
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return res
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
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* TreeNode left;
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* TreeNode right;
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* TreeNode() {}
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* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
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class Solution {
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public List<Double> averageOfLevels(TreeNode root) {
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List<Double> res = new ArrayList<>();
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Queue<TreeNode> q = new LinkedList<>();
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q.offer(root);
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while (!q.isEmpty()) {
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double s = 0, n = q.size();
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for (int i = 0; i < n; ++i) {
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TreeNode node = q.poll();
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s += node.val;
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if (node.left != null) {
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q.offer(node.left);
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}
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if (node.right != null) {
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q.offer(node.right);
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}
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}
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res.add(s / n);
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}
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return res;
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}
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}
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```
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### **...**

‎solution/0600-0699/0637.Average of Levels in Binary Tree/README_EN.md

+59-2
Original file line numberDiff line numberDiff line change
@@ -38,13 +38,70 @@ Hence return [3, 14.5, 11].
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### **Python3**
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```python
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# Definition for a binary tree node.
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# class TreeNode:
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# def __init__(self, val=0, left=None, right=None):
44+
# self.val = val
45+
# self.left = left
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# self.right = right
47+
class Solution:
48+
def averageOfLevels(self, root: TreeNode) -> List[float]:
49+
res = []
50+
q = collections.deque([root])
51+
while q:
52+
n = len(q)
53+
s = 0
54+
for _ in range(n):
55+
node = q.popleft()
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s += node.val
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if node.left:
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q.append(node.left)
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if node.right:
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q.append(node.right)
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res.append(s / n)
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return res
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```
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### **Java**
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```java
47-
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/**
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* Definition for a binary tree node.
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* public class TreeNode {
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* int val;
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* TreeNode left;
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* TreeNode right;
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* TreeNode() {}
75+
* TreeNode(int val) { this.val = val; }
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* TreeNode(int val, TreeNode left, TreeNode right) {
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* this.val = val;
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* this.left = left;
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* this.right = right;
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* }
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* }
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*/
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class Solution {
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public List<Double> averageOfLevels(TreeNode root) {
85+
List<Double> res = new ArrayList<>();
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Queue<TreeNode> q = new LinkedList<>();
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q.offer(root);
88+
while (!q.isEmpty()) {
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double s = 0, n = q.size();
90+
for (int i = 0; i < n; ++i) {
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TreeNode node = q.poll();
92+
s += node.val;
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if (node.left != null) {
94+
q.offer(node.left);
95+
}
96+
if (node.right != null) {
97+
q.offer(node.right);
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}
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}
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res.add(s / n);
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}
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return res;
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}
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}
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```
49106

50107
### **...**

‎solution/0600-0699/0637.Average of Levels in Binary Tree/Solution.java

+17-15
Original file line numberDiff line numberDiff line change
@@ -4,31 +4,33 @@
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* int val;
55
* TreeNode left;
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* TreeNode right;
7-
* TreeNode(int x) { val = x; }
7+
* TreeNode() {}
8+
* TreeNode(int val) { this.val = val; }
9+
* TreeNode(int val, TreeNode left, TreeNode right) {
10+
* this.val = val;
11+
* this.left = left;
12+
* this.right = right;
13+
* }
814
* }
915
*/
1016
class Solution {
11-
1217
public List<Double> averageOfLevels(TreeNode root) {
13-
if (root == null) return null;
14-
1518
List<Double> res = new ArrayList<>();
16-
LinkedList<TreeNode> queue = new LinkedList<>();
17-
queue.offer(root);
18-
19-
while (!queue.isEmpty()) {
20-
double sum = 0, size = queue.size();
21-
for (int i = 0; i < size; i ++) {
22-
TreeNode node = queue.poll();
23-
sum += node.val;
19+
Queue<TreeNode> q = new LinkedList<>();
20+
q.offer(root);
21+
while (!q.isEmpty()) {
22+
double s = 0, n = q.size();
23+
for (int i = 0; i < n; ++i) {
24+
TreeNode node = q.poll();
25+
s += node.val;
2426
if (node.left != null) {
25-
queue.offer(node.left);
27+
q.offer(node.left);
2628
}
2729
if (node.right != null) {
28-
queue.offer(node.right);
30+
q.offer(node.right);
2931
}
3032
}
31-
res.add(sum / size);
33+
res.add(s / n);
3234
}
3335
return res;
3436
}

‎solution/0600-0699/0637.Average of Levels in Binary Tree/Solution.py

+22
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,22 @@
1+
# Definition for a binary tree node.
2+
# class TreeNode:
3+
# def __init__(self, val=0, left=None, right=None):
4+
# self.val = val
5+
# self.left = left
6+
# self.right = right
7+
class Solution:
8+
def averageOfLevels(self, root: TreeNode) -> List[float]:
9+
res = []
10+
q = collections.deque([root])
11+
while q:
12+
n = len(q)
13+
s = 0
14+
for _ in range(n):
15+
node = q.popleft()
16+
s += node.val
17+
if node.left:
18+
q.append(node.left)
19+
if node.right:
20+
q.append(node.right)
21+
res.append(s / n)
22+
return res

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