[[Iterated digits squaring]] introduces RC the Project Euler Task #92. [[Combinations with repetitions]] introduce RC to the concept of generating all the combinations with repetitions of n types of things taken k at a time.
The purpose of this task is to combine these tasks as follows: :The collections of k items will be taken from [0,1,4,9,16,25,36,49,64,81] and must be obtained using code from [[Combinations with repetitions]]. The collection of k zeroes is excluded. :For each collection of k items determine if it translates to 1 using the rules from [[Iterated digits squaring]] :For each collection which translates to 1 determine the number of different ways, c say, in which the k items can be uniquely ordered. :Keep a running total of all the values of c obtained :Answer the Project Euler Task #92 question (k=7). :Answer the equivalent question for k=8,11,14. :Optionally answer the question for k=17. These numbers will be larger than the basic integer type for many languages, if it is not easy to use larger numbers it is not necessary for this task.
D
// Count how many number chains for Natural Numbers < 10**K end with a value of 1.
//
import std.stdio, std.range;
const struct CombRep {
immutable uint nt, nc;
private const ulong[] combVal;
this(in uint numType, in uint numChoice) pure nothrow @safe
in {
assert(0 < numType && numType + numChoice <= 64,
"Valid only for nt + nc <= 64 (ulong bit size)");
} body {
nt = numType;
nc = numChoice;
if (nc == 0)
return;
ulong v = (1UL << (nt - 1)) - 1;
// Init to smallest number that has nt-1 bit set
// a set bit is metaphored as a _type_ seperator.
immutable limit = v << nc;
ulong[] localCombVal;
// Limit is the largest nt-1 bit set number that has nc
// zero-bit a zero-bit means a _choice_ between _type_
// seperators.
while (v <= limit) {
localCombVal ~= v;
if (v == 0)
break;
// Get next nt-1 bit number.
immutable t = (v | (v - 1)) + 1;
v = t | ((((t & -t) / (v & -v)) >> 1) - 1);
}
this.combVal = localCombVal;
}
uint length() @property const pure nothrow @safe {
return combVal.length;
}
uint[] opIndex(in uint idx) const pure nothrow @safe {
return val2set(combVal[idx]);
}
int opApply(immutable int delegate(in ref uint[]) pure nothrow @safe dg)
pure nothrow @safe {
foreach (immutable v; combVal) {
auto set = val2set(v);
if (dg(set))
break;
}
return 1;
}
private uint[] val2set(in ulong v) const pure nothrow @safe {
// Convert bit pattern to selection set
immutable uint bitLimit = nt + nc - 1;
uint typeIdx = 0;
uint[] set;
foreach (immutable bitNum; 0 .. bitLimit)
if (v & (1 << (bitLimit - bitNum - 1)))
typeIdx++;
else
set ~= typeIdx;
return set;
}
}
// For finite Random Access Range.
auto combRep(R)(R types, in uint numChoice) /*pure*/ nothrow @safe
if (hasLength!R && isRandomAccessRange!R) {
ElementType!R[][] result;
foreach (const s; CombRep(types.length, numChoice)) {
ElementType!R[] r;
foreach (immutable i; s)
r ~= types[i];
result ~= r;
}
return result;
}
void main() {
int K = 17;
ulong[] F = [1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600, 6227020800, 87178291200, 1307674368000, 20922789888000, 355687428096000];
int[] N = [0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0];
ulong z = 0;
foreach (const e; combRep([0,1,4,9,16,25,36,49,64,81], K)) {
int s = 0;
foreach (const g; e) s += g;
if (N[s] == 0) continue;
int [int] n;
foreach (const g; e) n[g] += 1;
ulong gn = F[K];
foreach (const g; n.byValue()) gn /= F[g];
z += gn;
}
writefln ("\n(k=%d) In the range 1 to %d\n%d translate to 1 and %d translate to 89\n", K, (cast (ulong) (10))^^K-1,z,(cast (ulong) (10))^^K-1-z);
}
//(k=7) In the range 1 to 9999999
//1418853 translate to 1 and 8581146 translate to 89
//(k=8) In the range 1 to 99999999
//14255666 translate to 1 and 85744333 translate to 89
//(k=11) In the range 1 to 99999999999
//15091199356 translate to 1 and 84908800643 translate to 89
//(k=14) In the range 1 to 99999999999999
//13770853279684 translate to 1 and 86229146720315 translate to 89
//(k=17) In the range 1 to 99999999999999999
//12024696404768024 translate to 1 and 87975303595231975 translate to 89
Go
package main
import (
"fmt"
"math"
)
func endsWithOne(n int) bool {
sum := 0
for {
for n > 0 {
digit := n % 10
sum += digit * digit
n /= 10
}
if sum == 1 {
return true
}
if sum == 89 {
return false
}
n = sum
sum = 0
}
}
func main() {
ks := [...]int{7, 8, 11, 14, 17}
for _, k := range ks {
sums := make([]int64, k*81+1)
sums[0] = 1
sums[1] = 0
for n := 1; n <= k; n++ {
for i := n * 81; i > 0; i-- {
for j := 1; j < 10; j++ {
s := j * j
if s > i {
break
}
sums[i] += sums[i-s]
}
}
}
count1 := int64(0)
for i := 1; i <= k*81; i++ {
if endsWithOne(i) {
count1 += sums[i]
}
}
limit := int64(math.Pow10(k)) - 1
fmt.Println("For k =", k, "in the range 1 to", limit)
fmt.Println(count1, "numbers produce 1 and", limit-count1, "numbers produce 89\n")
}
}
For k = 7 in the range 1 to 9999999
1418853 numbers produce 1 and 8581146 numbers produce 89
For k = 8 in the range 1 to 99999999
14255666 numbers produce 1 and 85744333 numbers produce 89
For k = 11 in the range 1 to 99999999999
15091199356 numbers produce 1 and 84908800643 numbers produce 89
For k = 14 in the range 1 to 99999999999999
13770853279684 numbers produce 1 and 86229146720315 numbers produce 89
For k = 17 in the range 1 to 99999999999999999
12024696404768024 numbers produce 1 and 87975303595231975 numbers produce 89
Julia
using Combinatorics
function iterate(m::Integer)
while m != 1 && m != 89
s = 0
while m > 0 # compute sum of squares of digits
m, d = divrem(m, 10)
s += d ^ 2
end
m = s
end
return m
end
function testitersquares(numdigits)
items = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
onecount, eightyninecount = 0, 0
for combo in with_replacement_combinations(items, numdigits)
if any(x -> x != 0, combo)
pcount = Int(factorial(length(combo)) /
prod(y -> factorial(sum(x -> x == y, combo)), unique(combo)))
if iterate(sum(combo)) == 89
eightyninecount += pcount
else
onecount += pcount
end
end
end
println("For k = $numdigits, in the range 1 to $("9" ^ numdigits),\n" *
"$onecount numbers produce 1 and $eightyninecount numbers produce 89.\n")
end
for i in [7, 8, 11, 14, 17]
testitersquares(i)
end
For k = 2, in the range 1 to 99,
19 numbers produce 1 and 80 numbers produce 89.
For k = 7, in the range 1 to 9999999,
1418853 numbers produce 1 and 8581146 numbers produce 89.
For k = 8, in the range 1 to 99999999,
14255666 numbers produce 1 and 85744333 numbers produce 89.
For k = 11, in the range 1 to 99999999999,
15091199356 numbers produce 1 and 84908800643 numbers produce 89.
For k = 14, in the range 1 to 99999999999999,
13770853279684 numbers produce 1 and 86229146720315 numbers produce 89.
For k = 17, in the range 1 to 99999999999999999,
12024696404768024 numbers produce 1 and 87975303595231975 numbers produce 89.
Kotlin
To achieve reasonable performance, the Kotlin entry for the [[Iterated digits squaring]] task already used a similar approach to that required by this task for k = 8.
So the following generalizes that code to deal with values of k up to 17 (which requires 64 bit integers) and to count numbers where the squared digits sum sequence eventually ends in 1 rather than 89, albeit the sum of both must of course be 10 ^ k - 1.
// version 1.1.51
fun endsWithOne(n: Int): Boolean {
var digit: Int
var sum = 0
var nn = n
while (true) {
while (nn > 0) {
digit = nn % 10
sum += digit * digit
nn /= 10
}
if (sum == 1) return true
if (sum == 89) return false
nn = sum
sum = 0
}
}
fun main(args: Array<String>) {
val ks = intArrayOf(7, 8, 11, 14, 17)
for (k in ks) {
val sums = LongArray(k * 81 + 1)
sums[0] = 1
sums[1] = 0
var s: Int
for (n in 1 .. k) {
for (i in n * 81 downTo 1) {
for (j in 1 .. 9) {
s = j * j
if (s > i) break
sums[i] += sums[i - s]
}
}
}
var count1 = 0L
for (i in 1 .. k * 81) if (endsWithOne(i)) count1 += sums[i]
val limit = Math.pow(10.0, k.toDouble()).toLong() - 1
println("For k = $k in the range 1 to $limit")
println("$count1 numbers produce 1 and ${limit - count1} numbers produce 89\n")
}
}
For k = 7 in the range 1 to 9999999
1418853 numbers produce 1 and 8581146 numbers produce 89
For k = 8 in the range 1 to 99999999
14255666 numbers produce 1 and 85744333 numbers produce 89
For k = 11 in the range 1 to 99999999999
15091199356 numbers produce 1 and 84908800643 numbers produce 89
For k = 14 in the range 1 to 99999999999999
13770853279684 numbers produce 1 and 86229146720315 numbers produce 89
For k = 17 in the range 1 to 99999999999999999
12024696404768024 numbers produce 1 and 87975303595231975 numbers produce 89
Perl
use strict;
use feature 'say';
#use bigint; # un-comment to support the k = 17 case
sub comma { reverse ((reverse shift) =~ s/(.{3})/$1,/gr) =~ s/^,//r }
sub endsWithOne {
my($n) = @_;
my $digit;
my $sum = 0;
my $nn = $n;
while () {
while ($nn > 0) {
$digit = $nn % 10;
$sum += $digit**2;
$nn = int $nn / 10;
}
return 1 if $sum == 1;
return 0 if $sum == 89;
$nn = $sum;
$sum = 0;
}
}
my @ks = <7 8 11 14>;
for my $k (@ks) {
my @sums = <1 0>;
my $s;
for my $n (1 .. $k) {
for my $i (reverse 1 .. $n*81) {
for my $j (1 .. 9) {
last if ($s = $j**2) > $i;
$sums[$i] += $sums[$i-$s];
}
}
}
my $count1 = 0;
for my $i (1 .. $k*81) { $count1 += $sums[$i] if endsWithOne($i) }
my $limit = 10**$k - 1;
say "For k = $k in the range 1 to " . comma $limit;
say comma($count1) . ' numbers produce 1 and ' . comma($limit-$count1) . " numbers produce 89\n";
}
For k = 7 in the range 1 to 9,999,999
1,418,853 numbers produce 1 and 8,581,146 numbers produce 89
For k = 8 in the range 1 to 99,999,999
14,255,666 numbers produce 1 and 85,744,333 numbers produce 89
For k = 11 in the range 1 to 99,999,999,999
15,091,199,356 numbers produce 1 and 84,908,800,643 numbers produce 89
For k = 14 in the range 1 to 99,999,999,999,999
13,770,853,279,684 numbers produce 1 and 86,229,146,720,315 numbers produce 89
Perl 6
#!/usr/bin/env perl6
use v6;
sub endsWithOne($n --> Bool) {
my $digit;
my $sum = 0;
my $nn = $n;
loop {
while ($nn > 0) {
$digit = $nn % 10;
$sum += $digit²;
$nn = $nn div 10;
}
($sum == 1) and return True;
($sum == 89) and return False;
$nn = $sum;
$sum = 0;
}
}
my @ks = (7, 8, 11, 14, 17);
for @ks -> $k {
my @sums is default(0) = 1,0;
my $s;
for (1 .. $k) -> $n {
for ($n*81 ... 1) -> $i {
for (1 .. 9) -> $j {
$s = $j²;
if ($s > $i) { last };
@sums[$i] += @sums[$i-$s];
}
}
}
my $count1 = 0;
for (1 .. $k*81) -> $i { if (endsWithOne($i)) {$count1 += @sums[$i]} }
my $limit = 10**$k - 1;
say "For k = $k in the range 1 to $limit";
say "$count1 numbers produce 1 and ",$limit-$count1," numbers produce 89";
}
For k = 7 in the range 1 to 9999999
1418853 numbers produce 1 and 8581146 numbers produce 89
For k = 8 in the range 1 to 99999999
14255666 numbers produce 1 and 85744333 numbers produce 89
For k = 11 in the range 1 to 99999999999
15091199356 numbers produce 1 and 84908800643 numbers produce 89
For k = 14 in the range 1 to 99999999999999
13770853279684 numbers produce 1 and 86229146720315 numbers produce 89
For k = 17 in the range 1 to 99999999999999999
12024696404768024 numbers produce 1 and 87975303595231975 numbers produce 89
Phix
There is a solution to this on the [[Iterated_digits_squaring#Combinatorics_version|Iterated_digits_squaring]] page
Ruby
# Count how many number chains for Natural Numbers < 10**K end with a value of 1.
#
# Nigel_Galloway
# August 26th., 2014.
K = 17
F = Array.new(K+1){|n| n==0?1:(1..n).inject(:*)} #Some small factorials
g = -> n, gn=[n,0], res=0 { while gn[0]>0
gn = gn[0].divmod(10)
res += gn[1]**2
end
return res==89?0:res
}
#An array: N[n]==1 means that n translates to 1, 0 means that it does not.
N = (G=Array.new(K*81+1){|n| n==0? 0:(i=g.call(n))==89 ? 0:i}).collect{|n| while n>1 do n = G[n] end; n }
z = 0 #Running count of numbers translating to 1
(0..9).collect{|n| n**2}.repeated_combination(K).each{|n| #Iterate over unique digit combinations
next if N[n.inject(:+)] == 0 #Count only ones
nn = Hash.new{0} #Determine how many numbers this digit combination corresponds to
n.each{|n| nn[n] += 1} #and
z += nn.values.inject(F[K]){|gn,n| gn/F[n]} #Add to the count of numbers terminating in 1
}
puts "\nk=(#{K}) in the range 1 to #{10**K-1}\n#{z} numbers produce 1 and #{10**K-1-z} numbers produce 89"
#(k=7) in the range 1 to 9999999
#1418853 numbers produce 1 and 8581146 numbers produce 89
#(k=8) in the range 1 to 99999999
#14255666 numbers produce 1 and 85744333 numbers produce 89
#(k=11) in the range 1 to 99999999999
#15091199356 numbers produce 1 and 84908800643 numbers produce 89
#(k=14) in the range 1 to 99999999999999
#13770853279684 numbers produce 1 and 86229146720315 numbers produce 89
#(k=17) in the range 1 to 99999999999999999
#12024696404768024 numbers produce 1 and 87975303595231975 numbers produce 89
zkl
fcn countNumberChains(K){
F:=(K+1).pump(List,fcn(n){ (1).reduce(n,'*,1) }); #Some small factorials
g:=fcn(n){
gn,res:=L(n,0),0;
while(gn[0]>0){ gn=gn[0].divr(10); res+=gn[1].pow(2); }
if(res==89) 0 else res
};
#An array: N[n]==1 means that n translates to 1, 0 means that it does not.
n,G:=K*81+1,n.pump(List,g);
N:=n.pump(List,'wrap(n){ n=g(n); while(n>1){ n=G[n] } n });
z:=([0..9].pump(List,fcn(n){ n*n }):Utils.Helpers.combosKW(K,_)) #combos of (0,1,4,9,16,25,36,49,64,81)
.reduce('wrap(z,ds){ #Iterate over unique digit combinations
if(N[ds.sum(0)]==0) return(z); #Count only ones
nn:=Dictionary(); #Determine how many numbers this digit combination corresponds to
ds.pump(Void,nn.incV); #and (eg (0,0,0,0,0,1,9)-->(0:5, 1:1, 9:1)
z + nn.values.reduce( #Add to the count of numbers terminating in 1
'wrap(gn,n){ gn/F[n] },F[K]);
},0);
println("\nk=(%d) in the range 1 to %,d".fmt(K,(10).pow(K)-1));
println("%,d numbers produce 1 and %,d numbers produce 89".fmt(z,(10).pow(K)-1-z));
z
}
combosKW(k,sequence) is lazy, which, in this case, is quite a bit faster than the non-lazy version.
foreach K in (T(7,8,11,14,17)){ countNumberChains(K) }
k=(7) in the range 1 to 9,999,999
1,418,853 numbers produce 1 and 8,581,146 numbers produce 89
k=(8) in the range 1 to 99,999,999
14,255,666 numbers produce 1 and 85,744,333 numbers produce 89
k=(11) in the range 1 to 99,999,999,999
15,091,199,356 numbers produce 1 and 84,908,800,643 numbers produce 89
k=(14) in the range 1 to 99,999,999,999,999
13,770,853,279,684 numbers produce 1 and 86,229,146,720,315 numbers produce 89
k=(17) in the range 1 to 99,999,999,999,999,999
12,024,696,404,768,024 numbers produce 1 and 87,975,303,595,231,975 numbers produce 89