heap

http://www.youtube.com/watch?v=-6-xKgLOZPM

binary heap : it is a complete binary tree.

 

index from 0:

i left = 2i +1;  i right = 2i +2, i parent = (i-1)/2.

 

 

 

add.   添加到尾部.  和父亲对比. 大于就swap 父亲 自己。当最后是root的时候. root. left. right 对比.选择一个最大的swap root.

delte.  swap 尾部和delete  然后调整.   delete 尾部 直接删除.

 

 

 

build a heap:

1. iterated insertion

n total insertions, each worst than O(lgn).

worst case is O(nlgn).

2. linear time build-heap:

父比较left.如果小于.要 选父 left right最大的放到root.

 

 

binary heap sort.

O(nlgn)