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‎Problemset/0662-Maximum Width of Binary Tree/README.md

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# 662. Maximum Width of Binary Tree
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Given the `root` of a binary tree, return *the **maximum width** of the given tree*.
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The **maximum width** of a tree is the maximum **width** among all levels.
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The **width** of one level is defined as the length between the end-nodes (the leftmost and rightmost non-null nodes), where the null nodes between the end-nodes that would be present in a complete binary tree extending down to that level are also counted into the length calculation.
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It is **guaranteed** that the answer will in the range of a **32-bit** signed integer.
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#### Example 1:
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![](https://assets.leetcode.com/uploads/2021/05/03/width1-tree.jpg)
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<pre>
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<strong>Input:</strong> root = [1,3,2,5,3,null,9]
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<strong>Output:</strong> 4
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<strong>Explanation:</strong> The maximum width exists in the third level with length 4 (5,3,null,9).
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</pre>
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#### Example 2:
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![](https://assets.leetcode.com/uploads/2022/03/14/maximum-width-of-binary-tree-v3.jpg)
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<pre>
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<strong>Input:</strong> root = [1,3,2,5,null,null,9,6,null,7]
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<strong>Output:</strong> 7
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<strong>Explanation:</strong> The maximum width exists in the fourth level with length 7 (6,null,null,null,null,null,7).
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</pre>
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#### Example 3:
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![](https://assets.leetcode.com/uploads/2021/05/03/width3-tree.jpg)
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<pre>
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<strong>Input:</strong> root = [1,3,2,5]
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<strong>Output:</strong> 2
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<strong>Explanation:</strong> The maximum width exists in the second level with length 2 (3,2).
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</pre>
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#### Constraints:
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* The number of nodes in the tree is in the range `[1, 3000]`.
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* `-100 <= Node.val <= 100`
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## Solutions (Python)
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### 1. Solution
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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 widthOfBinaryTree(self, root: Optional[TreeNode]) -> int:
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currlevel = [(root, 0)]
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ret = 1
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while currlevel != []:
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nextlevel = []
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ret = max(ret, currlevel[-1][1] - currlevel[0][1] + 1)
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for node, x in currlevel:
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if node.left is not None:
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nextlevel.append((node.left, x << 1))
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if node.right is not None:
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nextlevel.append((node.right, (x << 1) + 1))
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currlevel = nextlevel
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return ret
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```

‎Problemset/0662-Maximum Width of Binary Tree/README_CN.md

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# 662. 二叉树最大宽度
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给你一棵二叉树的根节点 `root` ，返回树的 **最大宽度** 。
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树的 **最大宽度** 是所有层中最大的 **宽度** 。
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每一层的 **宽度** 被定义为该层最左和最右的非空节点（即，两个端点）之间的长度。将这个二叉树视作与满二叉树结构相同，两端点间会出现一些延伸到这一层的 `null` 节点，这些 `null` 节点也计入长度。
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题目数据保证答案将会在 **32 位** 带符号整数范围内。
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#### 示例 1:
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![](https://assets.leetcode.com/uploads/2021/05/03/width1-tree.jpg)
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<pre>
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<strong>输入:</strong> root = [1,3,2,5,3,null,9]
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<strong>输出:</strong> 4
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<strong>解释:</strong> 最大宽度出现在树的第 3 层，宽度为 4 (5,3,null,9) 。
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</pre>
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#### 示例 2:
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![](https://assets.leetcode.com/uploads/2022/03/14/maximum-width-of-binary-tree-v3.jpg)
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<pre>
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<strong>输入:</strong> root = [1,3,2,5,null,null,9,6,null,7]
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<strong>输出:</strong> 7
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<strong>解释:</strong> 最大宽度出现在树的第 4 层，宽度为 7 (6,null,null,null,null,null,7) 。
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</pre>
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#### 示例 3:
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![](https://assets.leetcode.com/uploads/2021/05/03/width3-tree.jpg)
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<pre>
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<strong>输入:</strong> root = [1,3,2,5]
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<strong>输出:</strong> 2
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<strong>解释:</strong> 最大宽度出现在树的第 2 层，宽度为 2 (3,2) 。
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</pre>
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#### 提示:
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* 树中节点的数目范围是 `[1, 3000]`
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* `-100 <= Node.val <= 100`
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## 题解 (Python)
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### 1. 题解
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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 widthOfBinaryTree(self, root: Optional[TreeNode]) -> int:
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currlevel = [(root, 0)]
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ret = 1
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while currlevel != []:
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nextlevel = []
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ret = max(ret, currlevel[-1][1] - currlevel[0][1] + 1)
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for node, x in currlevel:
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if node.left is not None:
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nextlevel.append((node.left, x << 1))
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if node.right is not None:
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nextlevel.append((node.right, (x << 1) + 1))
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currlevel = nextlevel
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return ret
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```

‎Problemset/0662-Maximum Width of Binary Tree/Solution.py

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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 widthOfBinaryTree(self, root: Optional[TreeNode]) -> int:
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currlevel = [(root, 0)]
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ret = 1
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while currlevel != []:
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nextlevel = []
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ret = max(ret, currlevel[-1][1] - currlevel[0][1] + 1)
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for node, x in currlevel:
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if node.left is not None:
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nextlevel.append((node.left, x << 1))
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if node.right is not None:
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nextlevel.append((node.right, (x << 1) + 1))
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currlevel = nextlevel
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return ret

‎README.md

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[657][657l] |[Robot Return to Origin][657] |![py]&nbsp;&nbsp;![rs]
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[658][658l] |[Find K Closest Elements][658] |![rs]
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[661][661l] |[Image Smoother][661] |![rs]
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[662][662l] |[Maximum Width of Binary Tree][662] |![py]
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[665][665l] |[Non-decreasing Array][665] |![py]
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[669][669l] |[Trim a Binary Search Tree][669] |![py]
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[670][670l] |[Maximum Swap][670] |![rs]
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[657]:Problemset/0657-Robot%20Return%20to%20Origin/README.md#657-robot-return-to-origin
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[658]:Problemset/0658-Find%20K%20Closest%20Elements/README.md#658-find-k-closest-elements
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[661]:Problemset/0661-Image%20Smoother/README.md#661-image-smoother
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[662]:Problemset/0662-Maximum%20Width%20of%20Binary%20Tree/README.md#662-maximum-width-of-binary-tree
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[665]:Problemset/0665-Non-decreasing%20Array/README.md#665-non-decreasing-array
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[669]:Problemset/0669-Trim%20a%20Binary%20Search%20Tree/README.md#669-trim-a-binary-search-tree
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[670]:Problemset/0670-Maximum%20Swap/README.md#670-maximum-swap
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[657l]:https://leetcode.com/problems/robot-return-to-origin/
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[658l]:https://leetcode.com/problems/find-k-closest-elements/
32033205
[661l]:https://leetcode.com/problems/image-smoother/
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[662l]:https://leetcode.com/problems/maximum-width-of-binary-tree/
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[665l]:https://leetcode.com/problems/non-decreasing-array/
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[669l]:https://leetcode.com/problems/trim-a-binary-search-tree/
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[670l]:https://leetcode.com/problems/maximum-swap/

‎README_CN.md

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[657][657l] |[机器人能否返回原点][657] |![py]&nbsp;&nbsp;![rs]
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[658][658l] |[找到 K 个最接近的元素][658] |![rs]
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[661][661l] |[图片平滑器][661] |![rs]
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[662][662l] |[二叉树最大宽度] |![py]
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[665][665l] |[非递减数列][665] |![py]
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[669][669l] |[修剪二叉搜索树][669] |![py]
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[670][670l] |[最大交换][670] |![rs]
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[657]:Problemset/0657-Robot%20Return%20to%20Origin/README_CN.md#657-机器人能否返回原点
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[658]:Problemset/0658-Find%20K%20Closest%20Elements/README_CN.md#658-找到-k-个最接近的元素
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[661]:Problemset/0661-Image%20Smoother/README_CN.md#661-图片平滑器
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[662]:Problemset/0662-Maximum%20Width%20of%20Binary%20Tree/README_CN.md#662-二叉树最大宽度
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[665]:Problemset/0665-Non-decreasing%20Array/README_CN.md#665-非递减数列
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[669]:Problemset/0669-Trim%20a%20Binary%20Search%20Tree/README_CN.md#669-修剪二叉搜索树
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[670]:Problemset/0670-Maximum%20Swap/README_CN.md#670-最大交换
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[657l]:https://leetcode.cn/problems/robot-return-to-origin/
32023204
[658l]:https://leetcode.cn/problems/find-k-closest-elements/
32033205
[661l]:https://leetcode.cn/problems/image-smoother/
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[662l]:https://leetcode.cn/problems/maximum-width-of-binary-tree/
32043207
[665l]:https://leetcode.cn/problems/non-decreasing-array/
32053208
[669l]:https://leetcode.cn/problems/trim-a-binary-search-tree/
32063209
[670l]:https://leetcode.cn/problems/maximum-swap/

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