Problem #46

Problem link
Solution:

package main

import (
    "math"
)

func main() {
    arr := make([]bool, 1000000)
    arr[0], arr[1], arr[2] = false, false, true
    i := 3
    var composite, found bool
    var tmp, tmp2 int
loop:
    for {
        composite = false
    inner:
        for j := 2; j < i; j++ {
            if arr[j] && i%j == 0 {
                composite = true
                break inner
            }
        }
        if composite {
            found = false
        inner2:
            for j := 2; j < i; j++ {
                if arr[j] {
                    tmp = (i - j)
                    if tmp2 = int(math.Sqrt(float64(tmp / 2))); tmp%2 == 0 && tmp2*tmp2 == tmp/2 {
                        found = true
                        break inner2
                    }
                }
            }
            if !found {
                println(i)
                break loop
            }
        } else { //prime
            arr[i] = true
        }
        i += 2
    }
}

Result: 5777
Time: 0m0.043s