47 lines
1.2 KiB
Go
47 lines
1.2 KiB
Go
package tree
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// FindOrder determines the correct order according to these rules:
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// 1. A node cannot come before all of its parents have been included.
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// 2. At any given time, the lowest-lettered available step must be executed.
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func FindOrder(root *Node) []*Node {
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seen := map[rune]bool{
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0: true,
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}
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order := []*Node{}
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for {
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// continuously loop over the tree, retrieving the next usable node.
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candidates := findCandidates(root, seen)
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if len(candidates) == 0 {
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return order
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}
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sortNodes(candidates)
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order = append(order, candidates[0])
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seen[candidates[0].Name] = true
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}
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}
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func findCandidates(node *Node, seen map[rune]bool) []*Node {
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candidates := []*Node{}
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// if we've been seen before, we're clear to recurse
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if seen[node.Name] == true {
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for _, child := range node.Children {
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candidates = append(candidates, findCandidates(child, seen)...)
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}
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return candidates
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}
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// add the node, but only if all its parents have been seen
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for _, parent := range node.Parents {
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if seen[parent.Name] == false {
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return candidates
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}
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}
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// We haven't seen this one before, and its parents are seen.
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// Return it as a candidate.
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return append(candidates, node)
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}
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