binhonglee/GlobeTrotte

package database

// NotExists - Return an array of int from haystack that aren't in the needles
func NotExists(haystack []int, needles []int) []int {
    needs := make(map[int]bool)
    notExists := make(map[int]bool)

    for _, v := range needles {
        needs[v] = true
    }

    for _, v := range haystack {
        if !needs[v] {
            notExists[v] = true
        }
    }
    toReturn := make([]int, len(notExists))
    i := 0
    for key := range notExists {
        toReturn[i] = key
        i++
    }

    return toReturn
}