155 lines
2.3 KiB
Go
155 lines
2.3 KiB
Go
package heap
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import (
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"474420502.top/eson/structure/compare"
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)
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type Heap struct {
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size int
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elements []interface{}
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Compare compare.Compare
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}
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func New(Compare compare.Compare) *Heap {
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h := &Heap{Compare: Compare}
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h.elements = make([]interface{}, 16, 16)
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return h
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}
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func (h *Heap) Size() int {
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return h.size
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}
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func (h *Heap) Values() []interface{} {
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return h.elements[0:h.size]
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}
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func (h *Heap) grow() {
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ecap := len(h.elements)
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if h.size >= ecap {
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ecap = ecap << 1
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grow := make([]interface{}, ecap, ecap)
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copy(grow, h.elements)
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h.elements = grow
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}
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}
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func (h *Heap) Empty() bool {
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return h.size < 1
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}
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func (h *Heap) Clear() {
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h.size = 0
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}
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func (h *Heap) Reborn() {
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h.size = 0
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h.elements = make([]interface{}, 16, 16)
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}
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func (h *Heap) Top() (interface{}, bool) {
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if h.size != 0 {
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return h.elements[0], true
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}
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return nil, false
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}
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func (h *Heap) Push(v interface{}) {
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if v == nil {
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return
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}
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h.grow()
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curidx := h.size
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h.size++
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// up
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for curidx != 0 {
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pidx := (curidx - 1) >> 1
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pvalue := h.elements[pidx]
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if h.Compare(v, pvalue) > 0 {
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h.elements[curidx] = pvalue
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curidx = pidx
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} else {
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break
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}
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}
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h.elements[curidx] = v
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}
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func (h *Heap) slimming() {
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elen := len(h.elements)
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if elen >= 32 {
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ecap := elen >> 1
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if h.size <= ecap {
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ecap = elen - (ecap >> 1)
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slimming := make([]interface{}, ecap, ecap)
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copy(slimming, h.elements)
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h.elements = slimming
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}
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}
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}
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func (h *Heap) Pop() (interface{}, bool) {
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if h.size == 0 {
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return nil, false
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}
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curidx := 0
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top := h.elements[curidx]
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h.size--
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h.slimming()
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if h.size == 0 {
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return top, true
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}
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downvalue := h.elements[h.size]
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var cidx, c1, c2 int
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var cvalue1, cvalue2, cvalue interface{}
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// down
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for {
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cidx = curidx << 1
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c2 = cidx + 2
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if c2 < h.size {
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cvalue2 = h.elements[c2]
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c1 = cidx + 1
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cvalue1 = h.elements[c1]
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if h.Compare(cvalue1, cvalue2) >= 0 {
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cidx = c1
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cvalue = cvalue1
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} else {
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cidx = c2
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cvalue = cvalue2
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}
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} else {
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c1 = cidx + 1
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if c1 < h.size {
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cvalue1 = h.elements[c1]
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cidx = c1
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cvalue = cvalue1
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} else {
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break
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}
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}
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if h.Compare(cvalue, downvalue) > 0 {
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h.elements[curidx] = cvalue
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curidx = cidx
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} else {
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break
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}
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}
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h.elements[curidx] = downvalue
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return top, true
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}
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