Problem #37

Problem link
Solution:

package main

import (
    "strconv"
)

func main() {
    arr := make([]bool, 1000000)
    left := make([]bool, 1000000)
    right := make([]bool, 1000000)

    //manuel setting for the values less than 10
    left[2], left[3], left[5], left[7] = true, true, true, true
    right[2], right[3], right[5], right[7] = true, true, true, true
    arr[0], arr[1], arr[6], arr[9] = true, true, true, true
    a := []int{3, 5, 7}
    for i := range a {
        for k := a[i] * 2; k < len(arr); k += a[i] {
            arr[k] = true
        }
    }

    //calculate other primes and check the condition.
    var k, tmp int
    prime, counter, sum := 11, 0, 0
    for {
        if right[prime/10] {
            right[prime] = true
        }
        tmp, _ = strconv.Atoi(strconv.Itoa(prime)[1:])
        if left[tmp] {
            left[prime] = true
            if right[prime] {
                sum += prime
                counter++
                if counter == 11 {
                    println(sum)
                    return
                }
            }
        }
        for k = prime * 2; k < len(arr); k += prime {
            arr[k] = true
        }
        for k = prime + 2; k < len(arr) && arr[k]; k += 2 {
        }
        if k < len(arr) {
            prime = k
        } else {
            break
        }
    }
}

Result: 748317
Time: 0m0.083s