PE-7 10001st prime

Posted 2021-01-25 miria-486

package main

import (
    "fmt"
    "math"
)

func main() {
    i := 2
    num := 1
    for num <= 10001 {
        if Prime(i) {
            num++
        }
        i++
    }
    fmt.Println(i - 1)
}
func Prime(num int) bool {
    if num == 2 || num == 3 {
        return true
    }
    if num%6 != 1 && num%6 != 5 {
        return false
    }
    tmp := int(math.Sqrt(float64(num)))
    for i := 5; i <= tmp; i += 6 {
        if num%i == 0 || num%(i+2) == 0 {
            return false
        }
    }
    return true
}

结果:104743