Problem #41

Problem link
Solution:

package main

import (
    "strconv"
    "strings"
)

func main() {
    a := make([]bool, 87654322)
    a[0], a[1] = true, true
    prime := 3
    var k int
    finished := false
    for !finished {
        for k = 2 * prime; k < len(a); k += prime {
            a[k] = true
        }
        for k = prime + 2; k < len(a) && a[k]; k += 2 {
        }
        if k < len(a) {
            prime = k
        } else {
            finished = true
        }
    }
    //a now has false values for the primes and multiples of 2
    //but we skip even numbers in our iteration.
    for i := int64(87654321); i > 0; i -= 2 {
        if !a[i] && isPandigital(i) {
            println(i)
            return
        }
    }
}

func isPandigital(in int64) bool {
    str := strconv.Itoa64(in)
    n := len(str)
    for i := 1; i <= n; i++ {
        if !strings.Contains(str, strconv.Itoa(i)) {
            return false
        }
    }
    return true
}

Result: 7652413
Time: 0m15.596s