43 lines
663 B
Go
43 lines
663 B
Go
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package iter
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import "math/rand"
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type seq struct {
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i []int
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}
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// Creates sequence of values from [0, n)
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func newSeq(n int) seq {
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return seq{make([]int, n, n)}
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}
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func (me seq) Index(i int) (ret int) {
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ret = me.i[i]
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if ret == 0 {
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ret = i
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}
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return
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}
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func (me seq) Len() int {
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return len(me.i)
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}
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// Remove the nth value from the sequence.
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func (me *seq) DeleteIndex(index int) {
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me.i[index] = me.Index(me.Len() - 1)
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me.i = me.i[:me.Len()-1]
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}
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func ForPerm(n int, callback func(i int) (more bool)) bool {
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s := newSeq(n)
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for s.Len() > 0 {
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r := rand.Intn(s.Len())
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if !callback(s.Index(r)) {
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return false
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}
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s.DeleteIndex(r)
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}
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return true
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}
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