38 lines
749 B
Go
38 lines
749 B
Go
package main
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// Go version of a prime number finder
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import (
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"fmt"
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"math"
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"os"
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"strconv"
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)
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// In stead of in place printing of each prime, it seems
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// fmt.Println is costly, and causes the program to take
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// 7x more time, so we gain speed at the expense of RAM
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// by storing them all in a slice and printing once
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func main() {
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if len(os.Args) < 2 {
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fmt.Println("Usage: go run primes.go [MAX]")
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return
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}
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//primes := make([]int, 0)
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max, _ := strconv.Atoi(os.Args[1])
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for i := 3; i < max; i += 2 {
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isPrime := true
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for j := 3; j <= int(math.Ceil(math.Sqrt(float64(i)))); j += 2 {
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if i%j == 0 {
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isPrime = false
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break
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}
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}
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if isPrime {
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//primes = append(primes, i)
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fmt.Println(i)
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}
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}
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//fmt.Println(primes)
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}
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