61 lines
1.0 KiB
Go
61 lines
1.0 KiB
Go
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package coding
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import (
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"maps"
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)
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type node struct {
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symbol byte
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count int
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}
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type Heap struct {
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nodes [256]node
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bySymbol map[byte]int
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}
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func NewHeap() *Heap {
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h := &Heap{
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bySymbol: map[byte]int{},
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}
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for i := 0; i < 256; i++ {
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h.nodes[i].symbol = byte(i)
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h.bySymbol[byte(i)] = i
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}
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return h
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}
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func (h Heap) Clone() *Heap {
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return &Heap{
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nodes: h.nodes,
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bySymbol: maps.Clone(h.bySymbol),
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}
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}
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func (h *Heap) IncrementSymbol(symbol byte) int {
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nodeIndex := h.bySymbol[symbol]
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h.nodes[nodeIndex].count++
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iterIndex := nodeIndex
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for iterIndex != 0 {
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parentIndex := h.parentIndex(iterIndex)
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if h.nodes[iterIndex].count <= h.nodes[parentIndex].count {
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break
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}
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h.nodes[iterIndex], h.nodes[parentIndex] = h.nodes[parentIndex], h.nodes[iterIndex]
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h.bySymbol[h.nodes[iterIndex].symbol] = iterIndex
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h.bySymbol[h.nodes[parentIndex].symbol] = parentIndex
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iterIndex = parentIndex
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}
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return nodeIndex
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}
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func (h Heap) parentIndex(nodeIndex int) int {
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return (nodeIndex - 1) / 2
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}
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