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# System prepended metadata

title: Week 3 (Mar 25)

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# Week 3 (Mar 25)

## 15. 3Sum

### Question

Given an integer array nums, return all the triplets  <mark>$[\;nums[i],\; nums[j],\; nums[k]\;]$</mark> such that  <mark>$i \neq j$</mark>,  <mark>$i \neq k$</mark>, and  <mark>$j \neq k$</mark>, and  <mark>$nums[i] + nums[j] + nums[k] == 0$</mark>.

Notice that the solution set must not contain duplicate triplets.

### Hand in homework before Saturday.

:::success
[Woody的作業](https://github.com/woodycatliu/leetcode/blob/main/0015_3Sum/15.swift)
[Allen的作業](https://github.com/allen870619/leetcode_practice/blob/main/1-500/15.%203Sum.playground/Contents.swift)
[Wen的作業](https://github.com/Tseng-W/LeetCodePractice/blob/main/LeetCodeStudy.playground/Pages/15.%203Sum.xcplaygroundpage/Contents.swift)
[xander的作業](https://github.com/Takumi47/30Plus/blob/main/30Plus/Problems/15_3Sum.swift)
[Roger的作業](https://github.com/GametreeRoger/LeetCode/blob/main/LeetCode15.playground/Contents.swift)
...`Continue filling by yourself`
:::

## 662. Maximum Width of Binary Tree

### Question

Given the <mark>$root$</mark> of a binary tree, return the **maximum width** of the given tree.

The **maximum width** of a tree is the maximum **width** among all levels.

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.

It is **guaranteed** that the answer will in the range of a **32-bit** signed integer.


### Hand in homework before Saturday.

:::success
[Woody的作業](https://github.com/woodycatliu/leetcode/blob/main/0662_MaximumWidthOfBinaryTree/662.swift)
[Allen的作業](https://github.com/allen870619/leetcode_practice/blob/main/501-1000/662.%20Maximum%20Width%20of%20Binary%20Tree.playground/Contents.swift)
[Wen的作業](https://github.com/Tseng-W/LeetCodePractice/blob/main/LeetCodeStudy.playground/Pages/662.%20Maximum%20Width%20of%20Binary%20Tree%20.xcplaygroundpage/Contents.swift) *leetCode runtime error*
[xander的作業](https://github.com/Takumi47/30Plus/blob/main/30Plus/Problems/662_MaximumWidthOfBinaryTree.swift)
[Roger的作業](https://github.com/GametreeRoger/LeetCode/blob/main/LeetCode662.playground/Contents.swift)
...`Continue filling by yourself`
:::