1 2 Priority 3 Comparator

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Comparator Interface Return negative value if o 1 is less than o 2, positive value if o 1 is more than o 2, and 0 otherwise. 4

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// Precondition: must not be an empty queue, otherwise it throws No. Such. Element. Exception. // Postcondition: return the most important object from this Priority. Queue. // Precondition: must not be an empty queue, otherwise it throws No. Such. Element. Exception. // Postcondition: remove and return the most important object from this Priority. Queue. 6

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List methods in this chapter comes from Linked. List class in Java. 11

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Heap is a complete binary tree 20

Smallest value is at the root for every subtree. 21

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Depends on avarage time of percolate. Up Resize array, this is O(n) The real operation. 31

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Let us follow the movement. 34

We finally get a heap at the end of all swaps. 35

// Postcondition: move the last element up the tree. The worst Depend on the height of the tree. Worst case happens when we need to swap up to the root. 36

Average time -percolate. Up 37

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remove. Min() – Be careful! 4 4 5 6 8 5 8 6 39

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Percolate. Down is 42

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The number of bits reduce to 300, 000 51

Can it be reduced even more? 52

How do we prevent ambiguity 53

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Put pair )character, frequency) into Priority Q 58

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Huffman class example 64

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Fields in the Huffman class 70

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Method process. Input 72

Method create. PQ 73

Method create. Huffman. Tree 74

Method calculate. Huffman. Codes 75

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Method save. To. File 78

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