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50 lines
798 B
Go
50 lines
798 B
Go
package main
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import (
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"container/heap"
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)
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// pqueue represents a min priority queue
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// it implements the heap.Interface interface
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type pqueue []*node
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func newPriorityQueue() *pqueue {
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pq := make(pqueue, 0)
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return &pq
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}
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func (pq pqueue) Len() int {
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return len(pq)
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}
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func (pq *pqueue) Push(x interface{}) {
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n := len(*pq)
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node := x.(*node)
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node.index = n
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*pq = append(*pq, node)
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}
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func (pq *pqueue) Pop() interface{} {
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old := *pq
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n := len(old)
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node := old[n-1]
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node.index = -1
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*pq = old[0 : n-1]
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return node
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}
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func (pq *pqueue) Update(node *node, value int) {
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node.cost = value
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heap.Fix(pq, node.index)
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}
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func (pq pqueue) Less(i, j int) bool {
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return pq[i].cost < pq[j].cost
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}
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func (pq pqueue) Swap(i, j int) {
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pq[i], pq[j] = pq[j], pq[i]
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pq[i].index = i
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pq[j].index = j
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}
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