Problem #14

Problem link
Solution:

package main

func main() {
    //allocate 4 MB of space at once
    arr := make([]int, 1000000)
    max, maxLoc, notFound, cur, steps := 0, 0, true, uint64(0), 0
    for i := 1; i < 1000000; i++ {
        notFound = true
        cur = uint64(i)
        steps = 0
        for notFound {
            if cur == 1 {
                notFound = false
                arr[i] = steps
                if steps > max {
                    max = steps
                    maxLoc = i
                }
            } else if cur < uint64(i) {
                notFound = false
                steps = steps + arr[cur]
                arr[i] = steps
                if steps > max {
                    max = steps
                    maxLoc = i
                }
            } else {
                if cur%2 == 0 {
                    cur /= 2
                } else {
                    cur = 3*cur + 1
                }
            }
            steps++
        }
    }
    println(max, maxLoc)
}

Result: 837799
Time: 0m0.271s