FindNumK MarkIt 寻找第k小的数，期望O(n)，最坏O(n).

FindNumKByQuickSort MarkIt 寻找第k小的数, 期望O(n)，最坏O(n**2).

Heapify initialize the heap.

InsertSort MarkIt 插入排序.

LocalSort MarkIt 对有k个关键字的n条数据，线性空间原址排序.

LowBit in the complement mode, (-x)'s binary expression is like ^(-x)+1 eg: 10: 0b00001010 -10: 0b10001010 0b11110101 0b11110110 (use biu.ToBinaryString to print it) reference: https://blog.csdn.net/zl10086111/article/details/80907428/.

PartitionRepetitive MarkIt 针对重复元素的快速排序partition.

ShortestPath Dijkstra, relating to questions like the shortest path of two nodes.

SiftDown move node i down to its proper position.

DisjointSet union-find algorithm https://www.geeksforgeeks.org/introduction-to-disjoint-set-data-structure-or-union-find-algorithm/.

DoublyListNode doubly-linked list.

ListNode linked list.

Trie # here we implement a trie based on lowercase.

Heap the implement in Golang is a Min Heap.