Min Heap Properties

1
Min Heap Properties

• Stored in an array
• First node starts at index 1
• Drawn as a full binary tree
• Parents always smaller than its children
• Left child 2parent index
• Right child 2parent index1
• Parent (left child index right childindex)/2
• Method
• walkdown
• heapify (Build Heap)
• walkkup
• Insert
• remove

2
Heap Method

• Walkdown
• Compare the node to its children and if children
  are smaller it swaps with the smallest child.
  Continues until
• Both children are larger
• Both children are NULL
• gt O(log2 N)

• Heapify
• Starts at the last internal node
• Call walkdown and continue on all previous node
• gt O(Nlog2 N)
• Walkup
• Swaps with parent if parent is larger
• Continue until
• Parent is smaller
• Parents index to 0

1
3
Heap Method

• Insert
• Add to the new available location
• (last element in array)
• Call walkup on the new inserted node

• Remove_Min
• swaps first element with the last element
• Remove the new last element
• Call walkdown on the new first node

4
Huffman code algorithm

• Count frequency for each character
• Put frequency into heap order
• Remove min twice
• Make a new node with children as the minimum,
  value equals the sum of the minimums
• Add new node into heap
• Continue 3-5 while more than 1 value is in the
  heap
• Assign 1 to left child and 0 to right child
• Traverse the tree, if node is a leaf, you can
  extract its Huffman code
• Replace text with code that have been found