First (unsuccessful) attempt at day 7.1.
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44
2018/internal/tree/breadthfirst.go
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44
2018/internal/tree/breadthfirst.go
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// BreadthFirstOrder and its companion functions ended up not giving the
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// right solution, but I'm leaving them here as a useful generic tree
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// algorithm.
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package tree
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func BreadthFirstOrder(root *Node) []*Node {
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seen := make(map[rune]bool)
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return breadthFirstOrderR(root, seen)
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}
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func findTreeRoot(depMap map[rune]*Node) *Node {
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for _, node := range depMap {
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if len(node.Parents) == 0 {
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return node
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}
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}
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return nil
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}
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func breadthFirstOrderR(node *Node, seen map[rune]bool) []*Node {
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order := []*Node{}
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// handle root
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if len(node.Parents) == 0 {
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order = append(order, node)
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seen[node.Name] = true
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}
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// add children we haven't seen before
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for _, child := range node.Children {
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if _, ok := seen[child.Name]; !ok {
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order = append(order, child)
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seen[child.Name] = true
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}
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}
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// recurse
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for _, child := range node.Children {
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order = append(order, breadthFirstOrderR(child, seen)...)
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}
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return order
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}
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