Golang Time Complexity: O(n) Space Complexity: O(n)

First: populates a hash map with all elements from the input array arr for quick lookups.

Second: For each element x, it checks if x - k and x + k exist in the hash map. if exist, count

The current element x is then removed from the hash map to prevent counting the same pair twice (e.g., counting (3, 5) when x=3 and then again when x=5)

func pairs(k int32, arr []int32) int32 {
exist := make(map[int32]bool)
for _, x := range arr {
    exist[x] = true
}

count := int32(0)
for _, x := range arr {
    if exist[x-k] {
        count++
    }
    if exist[x+k] {
        count++
    }
    exist[x] = false
}
return count

}

`