WeixiangYan/CodeTransOcean huggingface dataset:
Task: Euler method

C: #include <stdio.h>
#include <math.h>

typedef double (*deriv_f)(double, double);
#define FMT " %7.3f"

void ivp_euler(deriv_f f, double y, int step, int end_t)
{
	int t = 0;

	printf(" Step %2d: ", (int)step);
	do {
		if (t % 10 == 0) printf(FMT, y);
		y += step * f(t, y);
	} while ((t += step) <= end_t);
	printf("\n");
}

void analytic()
{
	double t;
	printf("    Time: ");
	for (t = 0; t <= 100; t += 10) printf(" %7g", t);
	printf("\nAnalytic: ");

	for (t = 0; t <= 100; t += 10)
		printf(FMT, 20 + 80 * exp(-0.07 * t));
	printf("\n");
}

double cooling(double t, double temp)
{
	return -0.07 * (temp - 20);
}

int main()
{
	analytic();
	ivp_euler(cooling, 100, 2, 100);
	ivp_euler(cooling, 100, 5, 100);
	ivp_euler(cooling, 100, 10, 100);

	return 0;
}




Go: package main

import (
    "fmt"
    "math"
)


type fdy func(float64, float64) float64




func eulerStep(f fdy, x, y, h float64) float64 {
    return y + h*f(x, y)
}






func newCoolingRate(k float64) func(float64) float64 {
    return func(deltaTemp float64) float64 {
        return -k * deltaTemp
    }
}



func newTempFunc(k, ambientTemp, initialTemp float64) func(float64) float64 {
    return func(time float64) float64 {
        return ambientTemp + (initialTemp-ambientTemp)*math.Exp(-k*time)
    }
}






func newCoolingRateDy(k, ambientTemp float64) fdy {
    crf := newCoolingRate(k)
    
    
    
    return func(_, objectTemp float64) float64 {
        return crf(objectTemp - ambientTemp)
    }
}

func main() {
    k := .07
    tempRoom := 20.
    tempObject := 100.
    fcr := newCoolingRateDy(k, tempRoom)
    analytic := newTempFunc(k, tempRoom, tempObject)
    for _, deltaTime := range []float64{2, 5, 10} {
        fmt.Printf("Step size = %.1f\n", deltaTime)
        fmt.Println(" Time Euler's Analytic")
        temp := tempObject
        for time := 0.; time <= 100; time += deltaTime {
            fmt.Printf("%5.1f %7.3f %7.3f\n", time, temp, analytic(time))
            temp = eulerStep(fcr, time, temp, deltaTime)
        }
        fmt.Println()
    }
}
Task: Sequence of non-squares

C: #include <math.h>
#include <stdio.h>
#include <assert.h>

int nonsqr(int n) {
    return n + (int)(0.5 + sqrt(n));
    
}

int main() {
    int i;
    
    
    for (i = 1; i < 23; i++)
        printf("%d ", nonsqr(i));
    printf("\n");
    
    
    for (i = 1; i < 1000000; i++) {
        double j = sqrt(nonsqr(i));
        assert(j != floor(j));
    }
    return 0;
}




Go: package main

import (
    "fmt"
    "math"
)

func remarkable(n int) int {
    return n + int(.5+math.Sqrt(float64(n)))
}

func main() {
    
    fmt.Println("  n  r(n)")
    fmt.Println("---  ---")
    for n := 1; n <= 22; n++ {
        fmt.Printf("%3d  %3d\n", n, remarkable(n))
    }

    
    const limit = 1e6
    fmt.Println("\nChecking for squares for n <", limit)
    next := 2
    nextSq := 4
    for n := 1; n < limit; n++ {
        r := remarkable(n)
        switch {
        case r == nextSq:
            panic(n)
        case r > nextSq:
            fmt.Println(nextSq, "didn't occur")
            next++
            nextSq = next * next
        }
    }
    fmt.Println("No squares occur for n <", limit)
}
Task: Substring

C: 
#define _CRT_SECURE_NO_WARNINGS 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


void putm(char* string, size_t m)
{
    while(*string && m--)
        putchar(*string++);
}

int main(void)
{

    char string[] = 
        "Programs for other encodings (such as 8-bit ASCII, or EUC-JP)."

    int n = 3;
    int m = 4;
    char knownCharacter = '(';
    char knownSubstring[] = "encodings";

    putm(string+n-1, m );                       putchar('\n');
    puts(string+n+1);                           putchar('\n');
    putm(string, strlen(string)-1);             putchar('\n');
    putm(strchr(string, knownCharacter), m );   putchar('\n');
    putm(strstr(string, knownSubstring), m );   putchar('\n');

    return EXIT_SUCCESS;
}




Go: package main

import (
    "fmt"
    "strings"
)

func main() {
    s := "ABCDEFGH"
    n, m := 2, 3
    
    fmt.Println("Index: ", "01234567")
    fmt.Println("String:", s)
    
    fmt.Printf("Start %d, length %d:    %s\n", n, m, s[n : n+m])
    
    fmt.Printf("Start %d, to end:      %s\n", n, s[n:])
    
    fmt.Printf("All but last:         %s\n", s[:len(s)-1])
    
    dx := strings.IndexByte(s, 'D')
    fmt.Printf("Start 'D', length %d:  %s\n", m, s[dx : dx+m])
    
    sx := strings.Index(s, "DE")
    fmt.Printf(`Start "DE", length %d: %s`+"\n", m, s[sx : sx+m])
}
Task: JortSort

C: #include <stdio.h>
#include <stdlib.h>



int number_of_digits(int x){
    int NumberOfDigits;
    for(NumberOfDigits=0;x!=0;NumberOfDigits++){
        x=x/10;
    }
    return NumberOfDigits;
}

int* convert_array(char array[], int NumberOfElements)  
{
    int *convertedArray=malloc(NumberOfElements*sizeof(int));
    int originalElement, convertedElement;

    for(convertedElement=0, originalElement=0; convertedElement<NumberOfElements; convertedElement++)
    {
       convertedArray[convertedElement]=atoi(&array[originalElement]);
       originalElement+=number_of_digits(convertedArray[convertedElement])+1; 

    }
    return convertedArray;
}



int isSorted(int array[], int numberOfElements){
    int sorted=1;
    for(int counter=0;counter<numberOfElements;counter++){
        if(counter!=0 && array[counter-1]>array[counter]) sorted--;

    }
    return sorted;
}
int main(int argc, char* argv[])
{
    int* convertedArray;


    convertedArray=convert_array(*(argv+1), argc-1);



    if(isSorted(convertedArray, argc-1)==1) printf("Did you forgot to turn on your brain?! This array is already sorted!\n");
    else if(argc-1<=10) printf("Am I really supposed to sort this? Sort it by yourself!\n");
    else printf("Am I really supposed to sort this? Bhahahaha!\n");
    free(convertedArray);
    return 0;



}




Go: package main

import (
  "log"
  "sort"
)

func main() {
  log.Println(jortSort([]int{1, 2, 1, 11, 213, 2, 4})) 
  log.Println(jortSort([]int{0, 1, 0, 0, 0, 0}))       
  log.Println(jortSort([]int{1, 2, 4, 11, 22, 22}))    
  log.Println(jortSort([]int{0, 0, 0, 1, 2, 2}))       
}

func jortSort(a []int) bool {
  c := make([]int, len(a))
  copy(c, a)
  sort.Ints(a)
  for k, v := range c {
    if v == a[k] {
      continue
    } else {
      return false
    }
  }
  return true
}
Task: Leap year

C: #include <stdio.h>

int is_leap_year(unsigned year)
{
    return !(year & (year % 100 ? 3 : 15));
}

int main(void)
{
    const unsigned test_case[] = {
        1900, 1994, 1996, 1997, 2000, 2024, 2025, 2026, 2100
    };
    const unsigned n = sizeof test_case / sizeof test_case[0];

    for (unsigned i = 0; i != n; ++i) {
        unsigned year = test_case[i];
        printf("%u is %sa leap year.\n", year, is_leap_year(year) ? "" : "not ");
    }
    return 0;
}




Go: func isLeap(year int) bool {
    return year%400 == 0 || year%4 == 0 && year%100 != 0
}
Task: Combinations and permutations

C: #include <gmp.h>

void perm(mpz_t out, int n, int k)
{
	mpz_set_ui(out, 1);
	k = n - k;
	while (n > k) mpz_mul_ui(out, out, n--);
}

void comb(mpz_t out, int n, int k)
{
	perm(out, n, k);
	while (k) mpz_divexact_ui(out, out, k--);
}

int main(void)
{
	mpz_t x;
	mpz_init(x);

	perm(x, 1000, 969);
	gmp_printf("P(1000,969) = %Zd\n", x);

	comb(x, 1000, 969);
	gmp_printf("C(1000,969) = %Zd\n", x);
	return 0;
}




Go: package main

import (
	"fmt"
	"math/big"
)

func main() {
	var n, p int64
	fmt.Printf("A sample of permutations from 1 to 12:\n")
	for n = 1; n < 13; n++ {
		p = n / 3
		fmt.Printf("P(%d,%d) = %d\n", n, p, perm(big.NewInt(n), big.NewInt(p)))
	}
	fmt.Printf("\nA sample of combinations from 10 to 60:\n")
	for n = 10; n < 61; n += 10 {
		p = n / 3
		fmt.Printf("C(%d,%d) = %d\n", n, p, comb(big.NewInt(n), big.NewInt(p)))
	}
	fmt.Printf("\nA sample of permutations from 5 to 15000:\n")
	nArr := [...]int64{5, 50, 500, 1000, 5000, 15000}
	for _, n = range nArr {
		p = n / 3
		fmt.Printf("P(%d,%d) = %d\n", n, p, perm(big.NewInt(n), big.NewInt(p)))
	}
	fmt.Printf("\nA sample of combinations from 100 to 1000:\n")
	for n = 100; n < 1001; n += 100 {
		p = n / 3
		fmt.Printf("C(%d,%d) = %d\n", n, p, comb(big.NewInt(n), big.NewInt(p)))
	}
}

func fact(n *big.Int) *big.Int {
	if n.Sign() < 1 {
		return big.NewInt(0)
	}
	r := big.NewInt(1)
	i := big.NewInt(2)
	for i.Cmp(n) < 1 {
		r.Mul(r, i)
		i.Add(i, big.NewInt(1))
	}
	return r
}

func perm(n, k *big.Int) *big.Int {
	r := fact(n)
	r.Div(r, fact(n.Sub(n, k)))
	return r
}

func comb(n, r *big.Int) *big.Int {
	if r.Cmp(n) == 1 {
		return big.NewInt(0)
	}
	if r.Cmp(n) == 0 {
		return big.NewInt(1)
	}
	c := fact(n)
	den := fact(n.Sub(n, r))
	den.Mul(den, fact(r))
	c.Div(c, den)
	return c
}
Task: Sort numbers lexicographically

C: #include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int compareStrings(const void *a, const void *b) {
    const char **aa = (const char **)a;
    const char **bb = (const char **)b;
    return strcmp(*aa, *bb);
}

void lexOrder(int n, int *ints) {
    char **strs;
    int i, first = 1, last = n, k = n, len;
    if (n < 1) {
        first = n; last = 1; k = 2 - n;
    } 
    strs = malloc(k * sizeof(char *));
    for (i = first; i <= last; ++i) {
        if (i >= 1) len = (int)log10(i) + 2;
        else if (i == 0) len = 2;
        else len = (int)log10(-i) + 3; 
        strs[i-first] = malloc(len);
        sprintf(strs[i-first], "%d", i);
    }
    qsort(strs, k, sizeof(char *), compareStrings);
    for (i = 0; i < k; ++i) {
        ints[i] = atoi(strs[i]);
        free(strs[i]);
    }
    free(strs);
}

int main() {
    int i, j, k, n,  *ints;
    int numbers[5] = {0, 5, 13, 21, -22};
    printf("In lexicographical order:\n\n");
    for (i = 0; i < 5; ++i) {
        k = n = numbers[i];
        if (k < 1) k = 2 - k;
        ints = malloc(k * sizeof(int));
        lexOrder(n, ints);
        printf("%3d: [", n);
        for (j = 0; j < k; ++j) {
            printf("%d ", ints[j]);
        }
        printf("\b]\n");
        free(ints);
    }
    return 0;
}




Go: package main

import (
    "fmt"
    "sort"
    "strconv"
)

func lexOrder(n int) []int {
    first, last, k := 1, n, n
    if n < 1 {
        first, last, k = n, 1, 2-n
    }
    strs := make([]string, k)
    for i := first; i <= last; i++ {
        strs[i-first] = strconv.Itoa(i)
    }
    sort.Strings(strs)
    ints := make([]int, k)
    for i := 0; i < k; i++ {
        ints[i], _ = strconv.Atoi(strs[i])
    }
    return ints
}

func main() {
    fmt.Println("In lexicographical order:\n")
    for _, n := range []int{0, 5, 13, 21, -22} {
        fmt.Printf("%3d: %v\n", n, lexOrder(n))
    }
}
Task: Compare length of two strings

C: #include <stdio.h>
#include <stdlib.h>
#include <string.h>

int cmp(const int* a, const int* b)
{
    return *b - *a; 
}

void compareAndReportStringsLength(const char* strings[], const int n)
{
    if (n > 0)
    {
        char* has_length = "has length";
        char* predicate_max = "and is the longest string";
        char* predicate_min = "and is the shortest string";
        char* predicate_ave = "and is neither the longest nor the shortest string";

        int* si = malloc(2 * n * sizeof(int));
        if (si != NULL)
        {
            for (int i = 0; i < n; i++)
            {
                si[2 * i] = strlen(strings[i]);
                si[2 * i + 1] = i;
            }
            qsort(si, n, 2 * sizeof(int), cmp);

            int max = si[0];
            int min = si[2 * (n - 1)];

            for (int i = 0; i < n; i++)
            {
                int length = si[2 * i];
                char* string = strings[si[2 * i + 1]];
                char* predicate;
                if (length == max)
                    predicate = predicate_max;
                else if (length == min)
                    predicate = predicate_min;
                else
                    predicate = predicate_ave;
                printf("\"%s\" %s %d %s\n",
                    string, has_length, length, predicate);
            }

            free(si);
        }
        else
        {
            fputs("unable allocate memory buffer", stderr);
        }
    }
}

int main(int argc, char* argv[])
{
    char* list[] = { "abcd", "123456789", "abcdef", "1234567" };

    compareAndReportStringsLength(list, 4);

    return EXIT_SUCCESS;
}




Go: package main

import (
	"fmt"
	"os"
	"sort"
)

func main() {
	
	if len(os.Args) == 1 {
		compareStrings("abcd", "123456789", "abcdef", "1234567")
	} else {
		
		strings := os.Args[1:]
		compareStrings(strings...)
	}
}


func compareStrings(strings ...string) {
	
	
	sort.SliceStable(strings, func(i, j int) bool {
		return len(strings[i]) > len(strings[j])
	})

	for _, s := range strings {
		fmt.Printf("%d: %s\n", len(s), s)
	}
}
Task: Sorting algorithms_Shell sort

C: #include <stdio.h>

void shell_sort (int *a, int n) {
    int h, i, j, t;
    for (h = n; h /= 2;) {
        for (i = h; i < n; i++) {
            t = a[i];
            for (j = i; j >= h && t < a[j - h]; j -= h) {
                a[j] = a[j - h];
            }
            a[j] = t;
        }
    }
}

int main (int ac, char **av) {
    int a[] = {4, 65, 2, -31, 0, 99, 2, 83, 782, 1};
    int n = sizeof a / sizeof a[0];
    int i;
    for (i = 0; i < n; i++)
        printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
    shell_sort(a, n);
    for (i = 0; i < n; i++)
        printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
    return 0;
}




Go: package main

import "fmt"

var a = []int{170, 45, 75, -90, -802, 24, 2, 66}

func main() {
    fmt.Println("before:", a)
    for inc := len(a) / 2; inc > 0; inc = (inc + 1) * 5 / 11 {
        for i := inc; i < len(a); i++ {
            j, temp := i, a[i]
            for ; j >= inc && a[j-inc] > temp; j -= inc {
                a[j] = a[j-inc]
            }
            a[j] = temp
        }
    }
    fmt.Println("after: ", a)
}
Task: Doubly-linked list_Definition

C: 
#include <stdio.h>
#include <stdlib.h>

struct List {
   struct MNode *head;
   struct MNode *tail;
   struct MNode *tail_pred;
};

struct MNode {
   struct MNode *succ;
   struct MNode *pred;
};

typedef struct MNode *NODE;
typedef struct List *LIST;


LIST newList(void);


int isEmpty(LIST);


NODE getTail(LIST);


NODE getHead(LIST);


NODE addTail(LIST, NODE);


NODE addHead(LIST, NODE);


NODE remHead(LIST);


NODE remTail(LIST);


NODE insertAfter(LIST, NODE, NODE);


NODE removeNode(LIST, NODE);


LIST newList(void)
{
    LIST tl = malloc(sizeof(struct List));
    if ( tl != NULL )
    {
       tl->tail_pred = (NODE)&tl->head;
       tl->tail = NULL;
       tl->head = (NODE)&tl->tail;
       return tl;
    }
    return NULL;
}

int isEmpty(LIST l)
{
   return (l->head->succ == 0);
}

NODE getHead(LIST l)
{
  return l->head;
}

NODE getTail(LIST l)
{
  return l->tail_pred;
}


NODE addTail(LIST l, NODE n)
{
    n->succ = (NODE)&l->tail;
    n->pred = l->tail_pred;
    l->tail_pred->succ = n;
    l->tail_pred = n;
    return n;
}

NODE addHead(LIST l, NODE n)
{
    n->succ = l->head;
    n->pred = (NODE)&l->head;
    l->head->pred = n;
    l->head = n;
    return n;
}

NODE remHead(LIST l)
{
   NODE h;
   h = l->head;
   l->head = l->head->succ;
   l->head->pred = (NODE)&l->head;
   return h;
}

NODE remTail(LIST l)
{
   NODE t;
   t = l->tail_pred;
   l->tail_pred = l->tail_pred->pred;
   l->tail_pred->succ = (NODE)&l->tail;
   return t;
}

NODE insertAfter(LIST l, NODE r, NODE n)
{
   n->pred = r; n->succ = r->succ;
   n->succ->pred = n; r->succ = n;
   return n;
}

NODE removeNode(LIST l, NODE n)
{
   n->pred->succ = n->succ;
   n->succ->pred = n->pred;
   return n;
}




Go: type dlNode struct {
    int
    next, prev *dlNode
}





type dlList struct {
    members map[*dlNode]int
    head, tail **dlNode
}
Task: Letter frequency

C: 
int frequency[26];
int ch;
FILE* txt_file = fopen ("a_text_file.txt", "rt");


for (ch = 0; ch < 26; ch++)
    frequency[ch] = 0;

while (1) {
    ch = fgetc(txt_file);
    if (ch == EOF) break; 

    
    if ('a' <= ch && ch <= 'z')      
        frequency[ch-'a']++;
    else if ('A' <= ch && ch <= 'Z') 
        frequency[ch-'A']++;
}




Go: package main

import (
    "fmt"
    "io/ioutil"
    "sort"
    "unicode"
)

const file = "unixdict.txt"

func main() {
    bs, err := ioutil.ReadFile(file)
    if err != nil {
        fmt.Println(err)
        return
    }
    m := make(map[rune]int)
    for _, r := range string(bs) {
        m[r]++
    }
    
    lfs := make(lfList, 0, len(m))
    for l, f := range m {
        lfs = append(lfs, &letterFreq{l, f})
    }
    sort.Sort(lfs)
    fmt.Println("file:", file)
    fmt.Println("letter  frequency")
    for _, lf := range lfs {
        if unicode.IsGraphic(lf.rune) {
            fmt.Printf("   %c    %7d\n", lf.rune, lf.freq)
        } else {
            fmt.Printf("%U  %7d\n", lf.rune, lf.freq)
        }
    }
}

type letterFreq struct {
    rune
    freq int
}
type lfList []*letterFreq

func (lfs lfList) Len() int { return len(lfs) }
func (lfs lfList) Less(i, j int) bool {
    switch fd := lfs[i].freq - lfs[j].freq; {
    case fd < 0:
        return false
    case fd > 0:
        return true
    }
    return lfs[i].rune < lfs[j].rune
}
func (lfs lfList) Swap(i, j int) {
    lfs[i], lfs[j] = lfs[j], lfs[i]
}
Task: Permutation test

C: #include <stdio.h>

int data[] = {  85, 88, 75, 66, 25, 29, 83, 39, 97,
                68, 41, 10, 49, 16, 65, 32, 92, 28, 98 };

int pick(int at, int remain, int accu, int treat)
{
        if (!remain) return (accu > treat) ? 1 : 0;

        return  pick(at - 1, remain - 1, accu + data[at - 1], treat) +
                ( at > remain ? pick(at - 1, remain, accu, treat) : 0 );
}

int main()
{
        int treat = 0, i;
        int le, gt;
        double total = 1;
        for (i = 0; i < 9; i++) treat += data[i];
        for (i = 19; i > 10; i--) total *= i;
        for (i = 9; i > 0; i--) total /= i;

        gt = pick(19, 9, 0, treat);
        le = total - gt;

        printf("<= : %f%%  %d\n > : %f%%  %d\n",
               100 * le / total, le, 100 * gt / total, gt);
        return 0;
}




Go: package main

import "fmt"

var tr = []int{85, 88, 75, 66, 25, 29, 83, 39, 97}
var ct = []int{68, 41, 10, 49, 16, 65, 32, 92, 28, 98}

func main() {
    
    all := make([]int, len(tr)+len(ct))
    copy(all, tr)
    copy(all[len(tr):], ct)

    
    var sumAll int
    for _, r := range all {
        sumAll += r
    }

    
    
    
    sd := func(trc []int) int {
        var sumTr int
        for _, x := range trc {
            sumTr += all[x]
        }
        return sumTr*len(ct) - (sumAll-sumTr)*len(tr)
    }

    
    a := make([]int, len(tr))
    for i, _ := range a {
        a[i] = i
    }
    sdObs := sd(a)

    
    
    var nLe, nGt int
    comb(len(all), len(tr), func(c []int) {
        if sd(c) > sdObs {
            nGt++
        } else {
            nLe++
        }
    })

    
    pc := 100 / float64(nLe+nGt)
    fmt.Printf("differences <= observed: %f%%\n", float64(nLe)*pc)
    fmt.Printf("differences  > observed: %f%%\n", float64(nGt)*pc)
}


func comb(n, m int, emit func([]int)) {
    s := make([]int, m)
    last := m - 1
    var rc func(int, int)
    rc = func(i, next int) {
        for j := next; j < n; j++ {
            s[i] = j
            if i == last {
                emit(s)
            } else {
                rc(i+1, j+1)
            }
        }
        return
    }
    rc(0, 0)
}
Task: Möbius function

C: #include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main() {
    const int MU_MAX = 1000000;
    int i, j;
    int *mu;
    int sqroot;

    sqroot = (int)sqrt(MU_MAX);

    mu = malloc((MU_MAX + 1) * sizeof(int));

    for (i = 0; i < MU_MAX;i++) {
        mu[i] = 1;
    }

    for (i = 2; i <= sqroot; i++) {
        if (mu[i] == 1) {
            
            for (j = i; j <= MU_MAX; j += i) {
                mu[j] *= -i;
            }
            
            for (j = i * i; j <= MU_MAX; j += i * i) {
                mu[j] = 0;
            }
        }
    }

    for (i = 2; i <= MU_MAX; i++) {
        if (mu[i] == i) {
            mu[i] = 1;
        } else if (mu[i] == -i) {
            mu[i] = -1;
        } else if (mu[i] < 0) {
            mu[i] = 1;
        } else if (mu[i] > 0) {
            mu[i] = -1;
        }
    }

    printf("First 199 terms of the möbius function are as follows:\n    ");
    for (i = 1; i < 200; i++) {
        printf("%2d  ", mu[i]);
        if ((i + 1) % 20 == 0) {
            printf("\n");
        }
    }

    free(mu);
    return 0;
}




Go: package main

import "fmt"

func möbius(to int) []int {
    if to < 1 {
        to = 1
    }
    mobs := make([]int, to+1) 
    primes := []int{2}
    for i := 1; i <= to; i++ {
        j := i
        cp := 0      
        spf := false 
        for _, p := range primes {
            if p > j {
                break
            }
            if j%p == 0 {
                j /= p
                cp++
            }
            if j%p == 0 {
                spf = true
                break
            }
        }
        if cp == 0 && i > 2 {
            cp = 1
            primes = append(primes, i)
        }
        if !spf {
            if cp%2 == 0 {
                mobs[i] = 1
            } else {
                mobs[i] = -1
            }
        }
    }
    return mobs
}

func main() {
    mobs := möbius(199)
    fmt.Println("Möbius sequence - First 199 terms:")
    for i := 0; i < 200; i++ {
        if i == 0 {
            fmt.Print("    ")
            continue
        }
        if i%20 == 0 {
            fmt.Println()
        }
        fmt.Printf("  % d", mobs[i])
    }
}
Task: Increment a numerical string

C: #include <stdio.h>
#include <string.h>
#include <stdlib.h>


char * incr(char *s)
{
	int i, begin, tail, len;
	int neg = (*s == '-');
	char tgt = neg ? '0' : '9';

	
	if (!strcmp(s, "-1")) {
		s[0] = '0', s[1] = '\0';
		return s;
	}

	len = strlen(s);
	begin = (*s == '-' || *s == '+') ? 1 : 0;

	
	for (tail = len - 1; tail >= begin && s[tail] == tgt; tail--);

	if (tail < begin && !neg) {
		
		if (!begin) s = realloc(s, len + 2);
		s[0] = '1';
		for (i = 1; i <= len - begin; i++) s[i] = '0';
		s[len + 1] = '\0';
	} else if (tail == begin && neg && s[1] == '1') {
		
		for (i = 1; i < len - begin; i++) s[i] = '9';
		s[len - 1] = '\0';
	} else { 
		for (i = len - 1; i > tail; i--)
			s[i] = neg ? '9' : '0';
		s[tail] += neg ? -1 : 1;
	}

	return s;
}

void string_test(const char *s)
{
	char *ret = malloc(strlen(s));
	strcpy(ret, s);

	printf("text: %s\n", ret);
	printf("  ->: %s\n", ret = incr(ret));
	free(ret);
}

int main()
{
	string_test("+0");
	string_test("-1");
	string_test("-41");
	string_test("+41");
	string_test("999");
	string_test("+999");
	string_test("109999999999999999999999999999999999999999");
	string_test("-100000000000000000000000000000000000000000000");

	return 0;
}




Go: package main
import "fmt"
import "strconv"
func main() {
  i, _ := strconv.Atoi("1234")
  fmt.Println(strconv.Itoa(i + 1))
}
Task: Strip a set of characters from a string

C: #include <string.h>
#include <stdio.h>
#include <stdlib.h>

  
char *strip_chars(const char *string, const char *chars)
{
  char * newstr = malloc(strlen(string) + 1);
  int counter = 0;

  for ( ; *string; string++) {
    if (!strchr(chars, *string)) {
      newstr[ counter ] = *string;
      ++ counter;
    }
  }

  newstr[counter] = 0;
  return newstr;
}

int main(void)
{
  char *new = strip_chars("She was a soul stripper. She took my heart!", "aei");
  printf("%s\n", new);

  free(new);
  return 0;
}




Go: package main

import (
    "fmt"
    "strings"
)

func stripchars(str, chr string) string {
    return strings.Map(func(r rune) rune {
        if strings.IndexRune(chr, r) < 0 {
            return r
        }
        return -1
    }, str)
}

func main() {
    fmt.Println(stripchars("She was a soul stripper. She took my heart!",
        "aei"))
}