
#### :a[424. Longest Repeating Character Replacement]{href=https://leetcode.com/problems/longest-repeating-character-replacement/}

sliding window

```
const is_ok = () => j - i + 1 - max(chars_freqs) <= k
```

#### 426. Convert Binary Search Tree to Sorted Doubly Linked List

inorder traversal

#### :a[428. Serialize and Deserialize N-ary Tree]{href=https://leetcode.com/problems/serialize-and-deserialize-n-ary-tree/ .nav}

bfs with children_size

---

TODO


#### [445. Add Two Numbers II](https://leetcode.com/problems/add-two-numbers-ii/)

Similar with [2. Add Two Numbers](https://leetcode.com/problems/add-two-numbers/); use a stack

#### :a[448. Find All Numbers Disappeared in an Array]{href=https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/ .nav}

![](./448-swap.png)

遍历数组，将每个数字交换到它理应出现的位置上，下面情况不用换：
- 当前数字本就出现在理应的位置上，跳过，不用换。
- 当前数字理应出现的位置上，已经存在当前数字，跳过，不用换。
再次遍历，如果当前位置没对应正确的数，如上图索引 4、5，则将对应的 5、6 加入 res。


#### :a[455. Assign Cookies]{href=https://leetcode.com/problems/assign-cookies/}

greedy 

#### :a[460. LFU Cache]{href=https://leetcode.com/problems/lfu-cache/}

**TODO**

#### :a[474. Ones and Zeroes]{href=https://leetcode.com/problems/ones-and-zeroes/}

2D backpack

#### :a[485. Max Consecutive Ones]{href=https://leetcode.com/problems/max-consecutive-ones/}

trivial

#### :a[487. Max Consecutive Ones II]{href=https://leetcode.com/problems/max-consecutive-ones-ii/}

sliding window


#### :a[496. Next Greater Element I]{href=https://leetcode.com/problems/next-greater-element-i/ .nav}

monotonic stack + hashmap




Scarlet Serenade

LeetCode Solutions | 401 - 500

424. Longest Repeating Character Replacement

426. Convert Binary Search Tree to Sorted Doubly Linked List

428. Serialize and Deserialize N-ary Tree

445. Add Two Numbers II

448. Find All Numbers Disappeared in an Array

455. Assign Cookies

460. LFU Cache

474. Ones and Zeroes

485. Max Consecutive Ones

487. Max Consecutive Ones II

496. Next Greater Element I