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Category talk:Go-rcu: Difference between revisions

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Category talk:Go-rcu (view source)

Revision as of 22:35, 27 April 2023

3,273 bytes added ,  1 year ago
m
Missing comma.
(→‎Source code: Added commatize option to PrintTable function.)
m (Missing comma.)
 
(7 intermediate revisions by the same user not shown)
Line 1:
===Source code===
<langsyntaxhighlight lang="go">package rcu
 
import "fmt"(
"fmt"
"golang.org/x/exp/constraints"
"math"
)
 
type Int = constraints.Integer
// Returns the larger of two ints.
 
func Max(x, y int) int {
// Returns the larger of two integers.
func Max[T Int](x, y T) T {
if x > y {
return x
Line 12 ⟶ 18:
}
 
// Returns the smaller of two intsintegers.
func Min[T Int](x, y intT) intT {
if x < y {
return x
Line 20 ⟶ 26:
}
 
// Returns the absolute value of an intinteger.
func Abs[T Int](x intT) intT {
if x < 0 {
return -x
Line 28 ⟶ 34:
}
 
// Returns the greatest common divisor of two intsintegers.
func Gcd[T Int](x, y intT) intT {
for y != 0 {
x, y = y, x%y
Line 36 ⟶ 42:
}
 
// Returns the least common multiple of two intsintegers.
func Lcm[T Int](x, y intT) intT { return Abs(x*y) / Gcd(x, y) }
 
// Returns whether or not an intinteger is prime.
func IsPrime[T Int](n intT) bool {
switch {
case n < 2:
Line 48 ⟶ 54:
case n%3 == 0:
return n == 3
case n%5 == 0:
return n == 5
default:
d := 5T(7)
forwheel d*d <:= n []T{4, 2, 4, 2, 4, 6, 2, 6}
if n%d == 0for {
for _, w := returnrange falsewheel {
} if d*d > n {
d += 2 return true
if n%d == 0 {}
returnif falsen%d == 0 {
return false
}
d += w
}
d += 4
}
return true
Line 68 ⟶ 78:
// c[i] is false if 'i' is prime or true if 'i' is composite.
// Optionally processes even numbers >= 4.
func PrimeSieve[T Int](limit intT, processEven bool) []bool {
limit++
// True denotes composite, false denotes prime.
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c[1] = true
if processEven {
for i := T(4); i < limit; i += 2 {
c[i] = true
}
}
p := T(3) // Start from 3.
for {
p2 := p * p
Line 99 ⟶ 109:
 
// Returns a slice of all primes up to and including 'limit'.
func Primes[T Int](limit intT) []intT {
c := PrimeSieve(limit, false)
if limit < 2 {
return []intT{}
}
primes := []intT{2}
for i := T(3); i < T(len(c)); i += 2 {
if !c[i] {
primes = append(primes, i)
Line 113 ⟶ 123:
}
 
// Sieves for primes up to and including 'n' and returns how many there are.
// Reverses a slice of ints in place.
// Uses an algorithm better suited to counting than the one used in the PrimeSieve method.
func ReverseInts(s []int) {
func PrimeCount[T Int](n T) int {
if n < 2 {
return 0
}
if n == 2 {
return 1
}
count := 1
k := (n-3)/2 + 1
marked := make([]bool, k) // all false by default
limit := (T(math.Sqrt(float64(n)))-3)/2 + 1
for i := T(0); i < limit; i++ {
if !marked[i] {
p := 2*i + 3
s := (p*p - 3) / 2
for j := s; j < k; j += p {
marked[j] = true
}
}
}
for i := T(0); i < k; i++ {
if !marked[i] {
count++
}
}
return count
}
 
// Returns the prime factors of 'n' in order using a wheel with basis [2, 3, 5].
func PrimeFactors[T Int](n T) []T {
if n < 2 {
return []T{}
}
inc := []T{4, 2, 4, 2, 4, 6, 2, 6}
var factors []T
for n%2 == 0 {
factors = append(factors, 2)
n = n / 2
}
for n%3 == 0 {
factors = append(factors, 3)
n = n / 3
}
for n%5 == 0 {
factors = append(factors, 5)
n = n / 5
}
for k, i := T(7), 0; k*k <= n; {
if n%k == 0 {
factors = append(factors, k)
n = n / k
} else {
k += inc[i]
i = (i + 1) % 8
}
}
if n > 1 {
factors = append(factors, n)
}
return factors
}
 
// Returns all the divisors of 'n' including 1 and 'n' itself.
func Divisors[T Int](n T) []T {
if n < 1 {
return []T{}
}
var divisors []T
var divisors2 []T
i := T(1)
k := T(1)
if n%2 == 1 {
k = 2
}
for ; i*i <= n; i += k {
if n%i == 0 {
divisors = append(divisors, i)
j := n / i
if j != i {
divisors2 = append(divisors2, j)
}
}
}
if len(divisors2) > 0 {
ReverseInts(divisors2)
divisors = append(divisors, divisors2...)
}
return divisors
}
 
// Returns all the divisors of 'n' excluding 'n'.
func ProperDivisors[T Int](n T) []T {
d := Divisors(n)
c := len(d)
if c <= 1 {
return []T{}
}
return d[0 : len(d)-1]
}
 
// Reverses a slice of integers in place.
func ReverseInts[T Int](s []T) {
for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
s[i], s[j] = s[j], s[i]
Line 120 ⟶ 232:
}
 
// Returns a slice of an intinteger's digits in base b.
func Digits[T Int](n T, b int) []int {
if n == 0 {
return []int{0}
Line 127 ⟶ 239:
var digits []int
for n > 0 {
digits = append(digits, int(n%T(b)))
n /= T(b)
}
ReverseInts(digits)
Line 134 ⟶ 246:
}
 
// Returns the sum of an intinteger's digits in base b.
func DigitSum[T Int](n T, b int) int {
sum := 0
for n > 0 {
sum += int(n % T(b))
n /= T(b)
}
return sum
}
 
// Returns the sum of a slice of integers.
// Adds thousand separators to an int.
func CommatizeSumInts[T Int](na int[]T) stringT {
sum := T(0)
for _, i := range a {
sum += i
}
return sum
}
 
// Returns the maximum of a slice of integers.
func MaxInts[T Int](a []T) T {
max := a[0]
for _, i := range a[1:] {
if i > max {
max = i
}
}
return max
}
 
// Returns the minimum of a slice of integers
func MinInts[T Int](a []T) T {
min := a[0]
for _, i := range a[1:] {
if i < min {
min = i
}
}
return min
}
 
// Adds thousand separators to an integer.
func Commatize[T Int](n T) string {
s := fmt.Sprintf("%d", n)
if n < 0 {
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}
 
// Prints a slice of intsintegers in tabular form with a given row and column size.
// and optionally comma separators.
func PrintTable(s []int, rowSize, colSize int, commas bool) {
func PrintTable[T Int](s []T, rowSize, colSize int, commas bool) {
for i := 0; i < len(s); i++ {
if !commas {
Line 175 ⟶ 319:
fmt.Println()
}
}</langsyntaxhighlight>
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