Nimber arithmetic: Difference between revisions

Content added Content deleted
m (Minor edit to Java code)
(Added Swift solution)
Line 994: Line 994:
println!("{} * {} = {}", a, b, nimprod(a, b));
println!("{} * {} = {}", a, b, nimprod(a, b));
}</lang>
}</lang>

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<pre>
+ | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
--- -------------------------------------------------
0 | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
1 | 1 0 3 2 5 4 7 6 9 8 11 10 13 12 15 14
2 | 2 3 0 1 6 7 4 5 10 11 8 9 14 15 12 13
3 | 3 2 1 0 7 6 5 4 11 10 9 8 15 14 13 12
4 | 4 5 6 7 0 1 2 3 12 13 14 15 8 9 10 11
5 | 5 4 7 6 1 0 3 2 13 12 15 14 9 8 11 10
6 | 6 7 4 5 2 3 0 1 14 15 12 13 10 11 8 9
7 | 7 6 5 4 3 2 1 0 15 14 13 12 11 10 9 8
8 | 8 9 10 11 12 13 14 15 0 1 2 3 4 5 6 7
9 | 9 8 11 10 13 12 15 14 1 0 3 2 5 4 7 6
10 | 10 11 8 9 14 15 12 13 2 3 0 1 6 7 4 5
11 | 11 10 9 8 15 14 13 12 3 2 1 0 7 6 5 4
12 | 12 13 14 15 8 9 10 11 4 5 6 7 0 1 2 3
13 | 13 12 15 14 9 8 11 10 5 4 7 6 1 0 3 2
14 | 14 15 12 13 10 11 8 9 6 7 4 5 2 3 0 1
15 | 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

* | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
--- -------------------------------------------------
0 | 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
1 | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
2 | 0 2 3 1 8 10 11 9 12 14 15 13 4 6 7 5
3 | 0 3 1 2 12 15 13 14 4 7 5 6 8 11 9 10
4 | 0 4 8 12 6 2 14 10 11 15 3 7 13 9 5 1
5 | 0 5 10 15 2 7 8 13 3 6 9 12 1 4 11 14
6 | 0 6 11 13 14 8 5 3 7 1 12 10 9 15 2 4
7 | 0 7 9 14 10 13 3 4 15 8 6 1 5 2 12 11
8 | 0 8 12 4 11 3 7 15 13 5 1 9 6 14 10 2
9 | 0 9 14 7 15 6 1 8 5 12 11 2 10 3 4 13
10 | 0 10 15 5 3 9 12 6 1 11 14 4 2 8 13 7
11 | 0 11 13 6 7 12 10 1 9 2 4 15 14 5 3 8
12 | 0 12 4 8 13 1 9 5 6 10 2 14 11 7 15 3
13 | 0 13 6 11 9 4 15 2 14 3 8 5 7 10 1 12
14 | 0 14 7 9 5 11 2 12 10 4 13 3 15 1 8 6
15 | 0 15 5 10 1 14 4 11 2 13 7 8 3 12 6 9

21508 + 42689 = 62149
21508 * 42689 = 35202
</pre>

=={{header|Swift}}==
{{trans|Rust}}
<lang swift>import Foundation

// highest power of 2 that divides a given number
func hpo2(_ n: Int) -> Int {
n & -n
}

// base 2 logarithm of the highest power of 2 dividing a given number
func lhpo2(_ n: Int) -> Int {
var q: Int = 0
var m: Int = hpo2(n)
while m % 2 == 0 {
m >>= 1
q += 1
}
return q
}

// nim-sum of two numbers
func nimSum(x: Int, y: Int) -> Int {
x ^ y
}

// nim-product of two numbers
func nimProduct(x: Int, y: Int) -> Int {
if x < 2 || y < 2 {
return x * y
}
var h = hpo2(x);
if x > h {
return nimProduct(x: h, y: y) ^ nimProduct(x: x ^ h, y: y)
}
if hpo2(y) < y {
return nimProduct(x: y, y: x)
}
let xp = lhpo2(x)
let yp = lhpo2(y)
let comp = xp & yp
if comp == 0 {
return x * y
}
h = hpo2(comp)
return nimProduct(x: nimProduct(x: x >> h, y: y >> h), y: 3 << (h - 1))
}

func printTable(n: Int, op: Character, function: (Int, Int) -> Int) {
print(" \(op) |", terminator: "")
for a in 0...n {
print(String(format: "%3d", a), terminator: "")
}
print("\n--- -", terminator: "")
for _ in 0...n {
print("---", terminator: "")
}
print()
for b in 0...n {
print("\(String(format: "%2d", b)) |", terminator: "")
for a in 0...n {
print(String(format: "%3d", function(a, b)), terminator: "")
}
print()
}
}

printTable(n: 15, op: "+", function: nimSum)
print()
printTable(n: 15, op: "*", function: nimProduct)
let a: Int = 21508
let b: Int = 42689
print("\n\(a) + \(b) = \(nimSum(x: a, y: b))")
print("\(a) * \(b) = \(nimProduct(x: a, y: b))")</lang>


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