checker permutation of a-z in O(n) time

permutation.go

// IsPermutation checks permutations in strings of a-z in O(n) time.
// O(n+n) since both a & b must be the same length.
func IsPermutation(a, b string) bool {
    al, bl := len(a), len(b)
    
    if al != bl {
        return false
    }
    
    var checker [2]int
    
    for i := 0; i < al; i++ {
        // if the same char is encountered twice, it'll just
        // set the same bit to 1 again.
        checker[0] = checker[0] | (1 << uint(a[i]-97))
    }
    
    for i := 0; i < bl; i++ {
        checker[1] = checker[1] | (1 << uint(b[i]-97))
    }
    
    //print the binary values of checkers a and b
    //fmt.Printf("%b, %b\n", checker[0], checker[1])
    return checker[0] == checker[1]
}