WeixiangYan/CodeTransOcean huggingface dataset:
Task: Thiele's interpolation formula


C++: #include <cmath>
#include <iostream>
#include <iomanip>
#include <string.h>

constexpr unsigned int N = 32u;
double xval[N], t_sin[N], t_cos[N], t_tan[N];

constexpr unsigned int N2 = N * (N - 1u) / 2u;
double r_sin[N2], r_cos[N2], r_tan[N2];

double ρ(double *x, double *y, double *r, int i, int n) {
    if (n < 0)
        return 0;
    if (!n)
        return y[i];

    unsigned int idx = (N - 1 - n) * (N - n) / 2 + i;
    if (r[idx] != r[idx])
        r[idx] = (x[i] - x[i + n]) / (ρ(x, y, r, i, n - 1) - ρ(x, y, r, i + 1, n - 1)) + ρ(x, y, r, i + 1, n - 2);
    return r[idx];
}

double thiele(double *x, double *y, double *r, double xin, unsigned int n) {
    return n > N - 1 ? 1. : ρ(x, y, r, 0, n) - ρ(x, y, r, 0, n - 2) + (xin - x[n]) / thiele(x, y, r, xin, n + 1);
}

inline auto i_sin(double x) { return thiele(t_sin, xval, r_sin, x, 0); }
inline auto i_cos(double x) { return thiele(t_cos, xval, r_cos, x, 0); }
inline auto i_tan(double x) { return thiele(t_tan, xval, r_tan, x, 0); }

int main() {
    constexpr double step = .05;
    for (auto i = 0u; i < N; i++) {
        xval[i] = i * step;
        t_sin[i] = sin(xval[i]);
        t_cos[i] = cos(xval[i]);
        t_tan[i] = t_sin[i] / t_cos[i];
    }
    for (auto i = 0u; i < N2; i++)
        r_sin[i] = r_cos[i] = r_tan[i] = NAN;

    std::cout << std::setw(16) << std::setprecision(25)
              << 6 * i_sin(.5) << std::endl
              << 3 * i_cos(.5) << std::endl
              << 4 * i_tan(1.) << std::endl;

    return 0;
}



Go: package main

import (
    "fmt"
    "math"
)

func main() {
    
    const nn = 32
    const step = .05
    xVal := make([]float64, nn)
    tSin := make([]float64, nn)
    tCos := make([]float64, nn)
    tTan := make([]float64, nn)
    for i := range xVal {
        xVal[i] = float64(i) * step
        tSin[i], tCos[i] = math.Sincos(xVal[i])
        tTan[i] = tSin[i] / tCos[i]
    }
    
    iSin := thieleInterpolator(tSin, xVal)
    iCos := thieleInterpolator(tCos, xVal)
    iTan := thieleInterpolator(tTan, xVal)
    
    fmt.Printf("%16.14f\n", 6*iSin(.5))
    fmt.Printf("%16.14f\n", 3*iCos(.5))
    fmt.Printf("%16.14f\n", 4*iTan(1))
}

func thieleInterpolator(x, y []float64) func(float64) float64 {
    n := len(x)
    ρ := make([][]float64, n)
    for i := range ρ {
        ρ[i] = make([]float64, n-i)
        ρ[i][0] = y[i]
    }
    for i := 0; i < n-1; i++ {
        ρ[i][1] = (x[i] - x[i+1]) / (ρ[i][0] - ρ[i+1][0])
    }
    for i := 2; i < n; i++ {
        for j := 0; j < n-i; j++ {
            ρ[j][i] = (x[j]-x[j+i])/(ρ[j][i-1]-ρ[j+1][i-1]) + ρ[j+1][i-2]
        }
    }
    
    ρ0 := ρ[0]
    return func(xin float64) float64 {
        var a float64
        for i := n - 1; i > 1; i-- {
            a = (xin - x[i-1]) / (ρ0[i] - ρ0[i-2] + a)
        }
        return y[0] + (xin-x[0])/(ρ0[1]+a)
    }
}
Task: Fibonacci word


C++: #include <string>
#include <map>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <iomanip>

double log2( double number ) {
   return ( log( number ) / log( 2 ) ) ;
}

double find_entropy( std::string & fiboword ) {
   std::map<char , int> frequencies ;
   std::for_each( fiboword.begin( ) , fiboword.end( ) ,
	 [ & frequencies ]( char c ) { frequencies[ c ]++ ; } ) ; 
   int numlen = fiboword.length( ) ;
   double infocontent = 0 ;
   for ( std::pair<char , int> p : frequencies ) {
      double freq = static_cast<double>( p.second ) / numlen ;
      infocontent += freq * log2( freq ) ;
   }
   infocontent *= -1 ;
   return infocontent ;
}

void printLine( std::string &fiboword , int n ) {
   std::cout << std::setw( 5 ) << std::left << n ;
   std::cout << std::setw( 12 ) << std::right << fiboword.size( ) ;
   std::cout << "  " << std::setw( 16 ) << std::setprecision( 13 ) 
      << std::left << find_entropy( fiboword ) ;
   std::cout << "\n" ;
}

int main( ) {
   std::cout << std::setw( 5 ) << std::left << "N" ;
   std::cout << std::setw( 12 ) << std::right << "length" ;
   std::cout << "  " << std::setw( 16 ) << std::left << "entropy" ; 
   std::cout << "\n" ;
   std::string firststring ( "1" ) ;
   int n = 1 ;
   printLine( firststring , n ) ;
   std::string secondstring( "0" ) ;
   n++ ;
   printLine( secondstring , n ) ;
   while ( n < 37 ) {
      std::string resultstring = firststring + secondstring ;
      firststring.assign( secondstring ) ;
      secondstring.assign( resultstring ) ;
      n++ ;
      printLine( resultstring , n ) ;
   }
   return 0 ;
}



Go: package main

import (
	"fmt"
	"math"
)


func entropy(s string) float64 {
	m := map[rune]float64{}
	for _, r := range s {
		m[r]++
	}
	hm := 0.
	for _, c := range m {
		hm += c * math.Log2(c)
	}
	l := float64(len(s))
	return math.Log2(l) - hm/l
}

const F_Word1 = "1"
const F_Word2 = "0"

func FibonacciWord(n int) string {
	a, b := F_Word1, F_Word2
	for ; n > 1; n-- {
		a, b = b, b+a
	}
	return a
}

func FibonacciWordGen() <-chan string {
	ch := make(chan string)
	go func() {
		a, b := F_Word1, F_Word2
		for {
			ch <- a
			a, b = b, b+a
		}
	}()
	return ch
}

func main() {
	fibWords := FibonacciWordGen()
	fmt.Printf("%3s %9s  %-18s  %s\n", "N", "Length", "Entropy", "Word")
	n := 1
	for ; n < 10; n++ {
		s := <-fibWords
		
		if s2 := FibonacciWord(n); s != s2 {
			fmt.Printf("For %d, generator produced %q, function produced %q\n", n, s, s2)
		}
		fmt.Printf("%3d %9d  %.16f  %s\n", n, len(s), entropy(s), s)
	}
	for ; n <= 37; n++ {
		s := <-fibWords
		fmt.Printf("%3d %9d  %.16f\n", n, len(s), entropy(s))
	}
}
Task: Find common directory path


C++: #include <algorithm>
#include <iostream>
#include <string>
#include <vector>

std::string longestPath( const std::vector<std::string> & , char ) ;

int main( ) {
   std::string dirs[ ] = {
      "/home/user1/tmp/coverage/test" ,
      "/home/user1/tmp/covert/operator" ,
      "/home/user1/tmp/coven/members" } ;
   std::vector<std::string> myDirs ( dirs , dirs + 3 ) ;
   std::cout << "The longest common path of the given directories is "
             << longestPath( myDirs , '/' ) << "!\n" ;
   return 0 ;
}

std::string longestPath( const std::vector<std::string> & dirs , char separator ) {
   std::vector<std::string>::const_iterator vsi = dirs.begin( ) ;
   int maxCharactersCommon = vsi->length( ) ;
   std::string compareString = *vsi ;
   for ( vsi = dirs.begin( ) + 1 ; vsi != dirs.end( ) ; vsi++ ) {
      std::pair<std::string::const_iterator , std::string::const_iterator> p = 
	 std::mismatch( compareString.begin( ) , compareString.end( ) , vsi->begin( ) ) ;
      if (( p.first - compareString.begin( ) ) < maxCharactersCommon ) 
	 maxCharactersCommon = p.first - compareString.begin( ) ;
   }
   std::string::size_type found = compareString.rfind( separator , maxCharactersCommon ) ;
   return compareString.substr( 0 , found ) ;
}



Go: package main

import (
	"fmt"
	"os"
	"path"
)

func CommonPrefix(sep byte, paths ...string) string {
	
	switch len(paths) {
	case 0:
		return ""
	case 1:
		return path.Clean(paths[0])
	}

	
	
	
	
	
	
	
	
	c := []byte(path.Clean(paths[0]))

	
	
	
	
	
	
	c = append(c, sep)

	
	for _, v := range paths[1:] {
		
		v = path.Clean(v) + string(sep)

		
		if len(v) < len(c) {
			c = c[:len(v)]
		}
		for i := 0; i < len(c); i++ {
			if v[i] != c[i] {
				c = c[:i]
				break
			}
		}
	}

	
	for i := len(c) - 1; i >= 0; i-- {
		if c[i] == sep {
			c = c[:i]
			break
		}
	}

	return string(c)
}

func main() {
	c := CommonPrefix(os.PathSeparator,
		
		"/home/user1/tmp/coverage/test",
		"/home/user1/tmp/covert/operator",
		"/home/user1/tmp/coven/members",
		"/home
		"/home/user1/././tmp/covertly/foo",
		"/home/bob/../user1/tmp/coved/bar",
	)
	if c == "" {
		fmt.Println("No common path")
	} else {
		fmt.Println("Common path:", c)
	}
}
Task: Verify distribution uniformity_Naive


C++: #include <map>
#include <iostream>
#include <cmath>

template<typename F>
 bool test_distribution(F f, int calls, double delta)
{
  typedef std::map<int, int> distmap;
  distmap dist;

  for (int i = 0; i < calls; ++i)
    ++dist[f()];

  double mean = 1.0/dist.size();

  bool good = true;

  for (distmap::iterator i = dist.begin(); i != dist.end(); ++i)
  {
    if (std::abs((1.0 * i->second)/calls - mean) > delta)
    {
      std::cout << "Relative frequency " << i->second/(1.0*calls)
                << " of result " << i->first
                << " deviates by more than " << delta
                << " from the expected value " << mean << "\n";
      good = false;
    }
  }

  return good;
}



Go: package main

import (
    "fmt"
    "math"
    "math/rand"
    "time"
)


func dice5() int {
    return rand.Intn(5) + 1
}


func dice7() (i int) {
    for {
        i = 5*dice5() + dice5()
        if i < 27 {
            break
        }
    }
    return (i / 3) - 1
}










func distCheck(f func() int, n int,
    repeats int, delta float64) (max float64, flatEnough bool) {
    count := make([]int, n)
    for i := 0; i < repeats; i++ {
        count[f()-1]++
    }
    expected := float64(repeats) / float64(n)
    for _, c := range count {
        max = math.Max(max, math.Abs(float64(c)-expected))
    }
    return max, max < delta
}


func main() {
    rand.Seed(time.Now().UnixNano())
    const calls = 1000000
    max, flatEnough := distCheck(dice7, 7, calls, 500)
    fmt.Println("Max delta:", max, "Flat enough:", flatEnough)
    max, flatEnough = distCheck(dice7, 7, calls, 500)
    fmt.Println("Max delta:", max, "Flat enough:", flatEnough)
}
Task: Stirling numbers of the second kind


C++: #include <algorithm>
#include <iomanip>
#include <iostream>
#include <map>
#include <gmpxx.h>

using integer = mpz_class;

class stirling2 {
public:
    integer get(int n, int k);
private:
    std::map<std::pair<int, int>, integer> cache_;
};

integer stirling2::get(int n, int k) {
    if (k == n)
        return 1;
    if (k == 0 || k > n)
        return 0;
    auto p = std::make_pair(n, k);
    auto i = cache_.find(p);
    if (i != cache_.end())
        return i->second;
    integer s = k * get(n - 1, k) + get(n - 1, k - 1);
    cache_.emplace(p, s);
    return s;
}

void print_stirling_numbers(stirling2& s2, int n) {
    std::cout << "Stirling numbers of the second kind:\nn/k";
    for (int j = 0; j <= n; ++j) {
        std::cout << std::setw(j == 0 ? 2 : 8) << j;
    }
    std::cout << '\n';
    for (int i = 0; i <= n; ++i) {
        std::cout << std::setw(2) << i << ' ';
        for (int j = 0; j <= i; ++j)
            std::cout << std::setw(j == 0 ? 2 : 8) << s2.get(i, j);
        std::cout << '\n';
    }
}

int main() {
    stirling2 s2;
    print_stirling_numbers(s2, 12);
    std::cout << "Maximum value of S2(n,k) where n == 100:\n";
    integer max = 0;
    for (int k = 0; k <= 100; ++k)
        max = std::max(max, s2.get(100, k));
    std::cout << max << '\n';
    return 0;
}



Go: package main

import (
    "fmt"
    "math/big"
)

func main() {
    limit := 100
    last := 12
    s2 := make([][]*big.Int, limit+1)
    for n := 0; n <= limit; n++ {
        s2[n] = make([]*big.Int, limit+1)
        for k := 0; k <= limit; k++ {
            s2[n][k] = new(big.Int)
        }
        s2[n][n].SetInt64(int64(1))
    }
    var t big.Int
    for n := 1; n <= limit; n++ {
        for k := 1; k <= n; k++ {
            t.SetInt64(int64(k))
            t.Mul(&t, s2[n-1][k])
            s2[n][k].Add(&t, s2[n-1][k-1])
        }
    }
    fmt.Println("Stirling numbers of the second kind: S2(n, k):")
    fmt.Printf("n/k")
    for i := 0; i <= last; i++ {
        fmt.Printf("%9d ", i)
    }
    fmt.Printf("\n--")
    for i := 0; i <= last; i++ {
        fmt.Printf("----------")
    }
    fmt.Println()
    for n := 0; n <= last; n++ {
        fmt.Printf("%2d ", n)
        for k := 0; k <= n; k++ {
            fmt.Printf("%9d ", s2[n][k])
        }
        fmt.Println()
    }
    fmt.Println("\nMaximum value from the S2(100, *) row:")
    max := new(big.Int).Set(s2[limit][0])
    for k := 1; k <= limit; k++ {
        if s2[limit][k].Cmp(max) > 0 {
            max.Set(s2[limit][k])
        }
    }
    fmt.Println(max)
    fmt.Printf("which has %d digits.\n", len(max.String()))
}
Task: Recaman's sequence


C++: #include <iostream>
#include <ostream>
#include <set>
#include <vector>

template<typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) {
    auto i = v.cbegin();
    auto e = v.cend();
    os << '[';
    if (i != e) {
        os << *i;
        i = std::next(i);
    }
    while (i != e) {
        os << ", " << *i;
        i = std::next(i);
    }
    return os << ']';
}

int main() {
    using namespace std;

    vector<int> a{ 0 };
    set<int> used{ 0 };
    set<int> used1000{ 0 };
    bool foundDup = false;
    int n = 1;
    while (n <= 15 || !foundDup || used1000.size() < 1001) {
        int next = a[n - 1] - n;
        if (next < 1 || used.find(next) != used.end()) {
            next += 2 * n;
        }
        bool alreadyUsed = used.find(next) != used.end();
        a.push_back(next);
        if (!alreadyUsed) {
            used.insert(next);
            if (0 <= next && next <= 1000) {
                used1000.insert(next);
            }
        }
        if (n == 14) {
            cout << "The first 15 terms of the Recaman sequence are: " << a << '\n';
        }
        if (!foundDup && alreadyUsed) {
            cout << "The first duplicated term is a[" << n << "] = " << next << '\n';
            foundDup = true;
        }
        if (used1000.size() == 1001) {
            cout << "Terms up to a[" << n << "] are needed to generate 0 to 1000\n";
        }
        n++;
    }

    return 0;
}



Go: package main

import "fmt"

func main() {
    a := []int{0}
    used := make(map[int]bool, 1001)
    used[0] = true
    used1000 := make(map[int]bool, 1001)
    used1000[0] = true
    for n, foundDup := 1, false; n <= 15 || !foundDup || len(used1000) < 1001; n++ {
        next := a[n-1] - n
        if next < 1 || used[next] {
            next += 2 * n
        }
        alreadyUsed := used[next]
        a = append(a, next)

        if !alreadyUsed {
            used[next] = true
            if next >= 0 && next <= 1000 {
                used1000[next] = true
            }
        }

        if n == 14 {
            fmt.Println("The first 15 terms of the Recaman's sequence are:", a)
        }

        if !foundDup && alreadyUsed {
            fmt.Printf("The first duplicated term is a[%d] = %d\n", n, next)
            foundDup = true
        }

        if len(used1000) == 1001 {
            fmt.Printf("Terms up to a[%d] are needed to generate 0 to 1000\n", n)
        }
    }
}
Task: Memory allocation


C++: #include <string>

int main()
{
  int* p;

  p = new int;    
  delete p;       

  p = new int(2); 
  delete p;       

  std::string* p2;

  p2 = new std::string; 
  delete p2;            

  p = new int[10]; 
  delete[] p;      

  p2 = new std::string[10]; 
  delete[] p2;              
}



Go: func inc(n int) {
    x := n + 1
    println(x)
}
Task: Integer sequence


C++: #include <cstdint>
#include <iostream>
#include <limits>

int main()
{
  auto i = std::uintmax_t{};
  
  while (i < std::numeric_limits<decltype(i)>::max())
    std::cout << ++i << '\n';
}



Go: package main

import "fmt"

func main() {
    for i := 1;; i++ {
        fmt.Println(i)
    }
}
Task: Bitwise operations




Go: package main

import "fmt"

func bitwise(a, b int16) {
	fmt.Printf("a:   %016b\n", uint16(a))
	fmt.Printf("b:   %016b\n", uint16(b))

	
	fmt.Printf("and: %016b\n", uint16(a&b))
	fmt.Printf("or:  %016b\n", uint16(a|b))
	fmt.Printf("xor: %016b\n", uint16(a^b))
	fmt.Printf("not: %016b\n", uint16(^a))

	if b < 0 {
		fmt.Println("Right operand is negative, but all shifts require an unsigned right operand (shift distance).")
		return
	}
	ua := uint16(a)
	ub := uint32(b)

	
	fmt.Printf("shl: %016b\n", uint16(ua<<ub))
	fmt.Printf("shr: %016b\n", uint16(ua>>ub))

	
	fmt.Printf("las: %016b\n", uint16(a<<ub))
	fmt.Printf("ras: %016b\n", uint16(a>>ub))

	
	fmt.Printf("rol: %016b\n", uint16(a<<ub|int16(uint16(a)>>(16-ub))))
	fmt.Printf("ror: %016b\n", uint16(int16(uint16(a)>>ub)|a<<(16-ub)))
}

func main() {
	var a, b int16 = -460, 6
	bitwise(a, b)
}



PHP: function bitwise($a, $b)
{
    function zerofill($a,$b) { 
        if($a>=0) return $a>>$b;
        if($b==0) return (($a>>1)&0x7fffffff)*2+(($a>>$b)&1); // this line shifts a 0 into the sign bit for compatibility, replace with "if($b==0) return $a;" if you need $b=0 to mean that nothing happens
        return ((~$a)>>$b)^(0x7fffffff>>($b-1)); 

    echo '$a AND $b: ' . $a & $b . '\n';
    echo '$a OR $b: ' . $a | $b . '\n';
    echo '$a XOR $b: ' . $a ^ $b . '\n';
    echo 'NOT $a: ' . ~$a . '\n';
    echo '$a << $b: ' . $a << $b . '\n'; // left shift  
    echo '$a >> $b: ' . $a >> $b . '\n'; // arithmetic right shift
    echo 'zerofill($a, $b): ' . zerofill($a, $b) . '\n'; // logical right shift
}
Task: Read a file line by line




Go: package main

import (
	"bufio"
	"fmt"
	"log"
	"os"
)

func init() {
	log.SetFlags(log.Lshortfile)
}

func main() {
	
	inputFile, err := os.Open("byline.go")
	if err != nil {
		log.Fatal("Error opening input file:", err)
	}

	
	
	
	defer inputFile.Close()

	scanner := bufio.NewScanner(inputFile)

	
	for scanner.Scan() {
		fmt.Println(scanner.Text())
	}

	
	
	if err := scanner.Err(); err != nil {
		log.Fatal(scanner.Err())
	}
}



PHP: <?php
$file = fopen(__FILE__, 'r'); // read current file
while ($line = fgets($file)) {
    $line = rtrim($line);      // removes linebreaks and spaces at end
    echo strrev($line) . "\n"; // reverse line and upload it
}
Task: Non-decimal radices_Convert




Go: package main

import (
    "fmt"
    "math/big"
    "strconv"
)

func main () {
    s := strconv.FormatInt(26, 16) 
    fmt.Println(s)

    i, err := strconv.ParseInt("1a", 16, 64) 
    if err == nil {
        fmt.Println(i)
    }
    b, ok := new(big.Int).SetString("1a", 16) 
    if ok {
        fmt.Println(b)
    }
}



PHP: base_convert("26", 10, 16); // returns "1a"
Task: Walk a directory_Recursively




Go: package main

import (
    "fmt"
    "os"
    "path/filepath"
)

func VisitFile(fp string, fi os.FileInfo, err error) error {
    if err != nil {
        fmt.Println(err) 
        return nil       
    }
    if fi.IsDir() {
        return nil 
    }
    matched, err := filepath.Match("*.mp3", fi.Name())
    if err != nil {
        fmt.Println(err) 
        return err       
    }
    if matched {
        fmt.Println(fp)
    }
    return nil
}

func main() {
    filepath.Walk("/", VisitFile)
}



PHP: function findFiles($dir = '.', $pattern = '/./'){
  $prefix = $dir . '/';
  $dir = dir($dir);
  while (false !== ($file = $dir->read())){
    if ($file === '.' || $file === '..') continue;
    $file = $prefix . $file;
    if (is_dir($file)) findFiles($file, $pattern);
    if (preg_match($pattern, $file)){
      echo $file . "\n";
    }
  }
}
findFiles('./foo', '/\.bar$/');
Task: CRC-32




Go: package main

import (
    "fmt"
    "hash/crc32"
)

func main() {
    s := []byte("The quick brown fox jumps over the lazy dog")
    result := crc32.ChecksumIEEE(s)
    fmt.Printf("%X\n", result)
}



PHP: printf("%x\n", crc32("The quick brown fox jumps over the lazy dog"));
Task: Classes




Go: package main

import "fmt"




type picnicBasket struct {
    nServings int 
    corkscrew bool
}


func (b *picnicBasket) happy() bool {
    return b.nServings > 1 && b.corkscrew
}









func newPicnicBasket(nPeople int) *picnicBasket {
    
    
    
    
    return &picnicBasket{nPeople, nPeople > 0}
}


func main() {
    var pb picnicBasket          
    pbl := picnicBasket{}        
    pbp := &picnicBasket{}       
    pbn := new(picnicBasket)     
    forTwo := newPicnicBasket(2) 
    
    forToo := &picnicBasket{nServings: 2, corkscrew: true}

    fmt.Println(pb.nServings, pb.corkscrew)
    fmt.Println(pbl.nServings, pbl.corkscrew)
    fmt.Println(pbp)
    fmt.Println(pbn)
    fmt.Println(forTwo)
    fmt.Println(forToo)
}



PHP: class MyClass {
    public static $classVar;
    public $instanceVar; // can also initialize it here
    function __construct() {
        $this->instanceVar = 0;
    }
    function someMethod() {
        $this->instanceVar = 1;
        self::$classVar = 3;
    }
}
$myObj = new MyClass();
Task: Kaprekar numbers




Go: package main

import (
    "fmt"
    "strconv"
)

func kaprekar(n uint64, base uint64) (bool, int) {
    order := 0
    if n == 1 {
        return true, -1
    }

    nn, power := n*n, uint64(1)
    for power <= nn {
        power *= base
        order++
    }

    power /= base
    order--
    for ; power > 1; power /= base {
        q, r := nn/power, nn%power
        if q >= n {
            return false, -1
        }

        if q+r == n {
            return true, order
        }

        order--
    }

    return false, -1
}

func main() {
    max := uint64(10000)
    fmt.Printf("Kaprekar numbers < %d:\n", max)
    for m := uint64(0); m < max; m++ {
        if is, _ := kaprekar(m, 10); is {
            fmt.Println("  ", m)
        }
    }

    
    max = 1e6
    var count int
    for m := uint64(0); m < max; m++ {
        if is, _ := kaprekar(m, 10); is {
            count++
        }
    }
    fmt.Printf("\nThere are %d Kaprekar numbers < %d.\n", count, max)

    
    const base = 17
    maxB := "1000000"
    fmt.Printf("\nKaprekar numbers between 1 and %s(base %d):\n", maxB, base)
    max, _ = strconv.ParseUint(maxB, base, 64)
    fmt.Printf("\n Base 10  Base %d        Square       Split\n", base)
    for m := uint64(2); m < max; m++ {
        is, pos := kaprekar(m, base)
        if !is {
            continue
        }
        sq := strconv.FormatUint(m*m, base)
        str := strconv.FormatUint(m, base)
        split := len(sq)-pos
        fmt.Printf("%8d  %7s  %12s  %6s + %s\n", m,
            str, sq, sq[:split], sq[split:]) 
    }
}



PHP: set_time_limit(300);

print_r(array_filter(range(1, 10000), 'isKaprekar'));
echo count(array_filter(range(1, 1000000), 'isKaprekar'));

function isKaprekar($n) {
    $a = $n * $n; 
    $b = bcmod("$a", "10");
    for ($d = 1, $t = 0; $a > 0; $d *= 10) {
        $b += $t * $d;
        if ($b > $n) break;
        $a = floor($a / 10);
        if ($b && $a + $b == $n) 
            return true;
        $t = bcmod("$a", "10");
    }
    return false;
}
Task: Anonymous recursion




Go: package main

import "fmt"

func main() {
    for _, n := range []int{0, 1, 2, 3, 4, 5, 10, 40, -1} {
        f, ok := arFib(n)
        if ok {
            fmt.Printf("fib %d = %d\n", n, f)
        } else {
            fmt.Println("fib undefined for negative numbers")
        }
    }
}

func arFib(n int) (int, bool) {
    switch {
    case n < 0:
        return 0, false
    case n < 2:
        return n, true
    }
    return yc(func(recurse fn) fn {
        return func(left, term1, term2 int) int {
            if left == 0 {
                return term1+term2
            }
            return recurse(left-1, term1+term2, term1)
        }
    })(n-2, 1, 0), true
}

type fn func(int, int, int) int
type ff func(fn) fn
type fx func(fx) fn

func yc(f ff) fn {
    return func(x fx) fn {
        return x(x)
    }(func(x fx) fn {
        return f(func(a1, a2, a3 int) int {
            return x(x)(a1, a2, a3)
        })
    })
}



PHP: <?php
function fib($n) {
    if ($n < 0)
        throw new Exception('Negative numbers not allowed');
    $f = function($n) { // This function must be called using call_user_func() only
        if ($n < 2)
            return 1;
        else {
            $g = debug_backtrace()[1]['args'][0];
            return call_user_func($g, $n-1) + call_user_func($g, $n-2);
        }
    };
    return call_user_func($f, $n);
}
echo fib(8), "\n";
?>