mirror of
https://github.com/octoleo/syncthing.git
synced 2024-11-15 01:34:05 +00:00
91 lines
2.0 KiB
Go
91 lines
2.0 KiB
Go
// Copyright (c) 2011 jnml. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build ignore
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// Let QRN be the number of quadratic residues of N. Let Q be QRN/N. From a
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// sorted list of primorial products < 2^32 find "record breakers". "Record
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// breaker" is N with new lowest Q.
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//
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// There are only 49 "record breakers" < 2^32.
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//
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// To run the example $ go run main.go
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package main
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import (
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"fmt"
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"math"
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"sort"
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"time"
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"github.com/cznic/mathutil"
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"github.com/cznic/sortutil"
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)
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func main() {
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pp := mathutil.PrimorialProductsUint32(0, math.MaxUint32, 32)
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sort.Sort(sortutil.Uint32Slice(pp))
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var bestN, bestD uint32 = 1, 1
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order, checks := 0, 0
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var ixDirty uint32
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m := make([]byte, math.MaxUint32>>3)
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for _, n := range pp {
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for i := range m[:ixDirty+1] {
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m[i] = 0
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}
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ixDirty = 0
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checks++
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limit0 := mathutil.QScaleUint32(n, bestN, bestD)
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if limit0 > math.MaxUint32 {
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panic(0)
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}
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limit := uint32(limit0)
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n64 := uint64(n)
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hi := n64 >> 1
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hits := uint32(0)
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check := true
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fmt.Printf("\r%10d %d/%d", n, checks, len(pp))
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t0 := time.Now()
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for i := uint64(0); i < hi; i++ {
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sq := uint32(i * i % n64)
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ix := sq >> 3
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msk := byte(1 << (sq & 7))
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if m[ix]&msk == 0 {
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hits++
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if hits >= limit {
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check = false
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break
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}
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}
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m[ix] |= msk
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if ix > ixDirty {
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ixDirty = ix
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}
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}
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adjPrime := ".." // Composite before
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if mathutil.IsPrime(n - 1) {
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adjPrime = "P." // Prime before
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}
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switch mathutil.IsPrime(n + 1) {
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case true:
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adjPrime += "P" // Prime after
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case false:
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adjPrime += "." // Composite after
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}
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if check && mathutil.QCmpUint32(hits, n, bestN, bestD) < 0 {
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order++
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d := time.Since(t0)
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bestN, bestD = hits, n
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q := float64(hits) / float64(n)
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fmt.Printf(
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"\r%2s #%03d %d %d %.2f %.2E %s %s %v\n",
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adjPrime, order, n, hits,
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1/q, q, d, time.Now().Format("15:04:05"), mathutil.FactorInt(n),
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)
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}
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}
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}
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