61 lines
1.1 KiB
Go
61 lines
1.1 KiB
Go
package main
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import "fmt"
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// a type that allows cyclic structures
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type node []*node
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// recursively print the contents of a node
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func (n *node) list() {
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if n == nil {
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fmt.Println(n)
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return
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}
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listed := map[*node]bool{nil: true}
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var r func(*node)
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r = func(n *node) {
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listed[n] = true
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fmt.Printf("%p -> %v\n", n, *n)
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for _, m := range *n {
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if !listed[m] {
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r(m)
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}
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}
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}
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r(n)
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}
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// construct a deep copy of a node
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func (n *node) ccopy() *node {
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if n == nil {
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return n
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}
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cc := map[*node]*node{nil: nil}
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var r func(*node) *node
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r = func(n *node) *node {
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c := make(node, len(*n))
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cc[n] = &c
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for i, m := range *n {
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d, ok := cc[m]
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if !ok {
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d = r(m)
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}
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c[i] = d
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}
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return &c
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}
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return r(n)
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}
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func main() {
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a := node{nil}
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c := &node{&node{&a}}
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a[0] = c
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c.list()
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cc := c.ccopy()
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fmt.Println("copy:")
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cc.list()
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fmt.Println("original:")
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c.list()
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}
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