WeixiangYan/CodeTransOcean huggingface dataset:
Task: Sierpinski carpet

C: #include <stdio.h>

int main()
{
	int i, j, dim, d;
	int depth = 3;

	for (i = 0, dim = 1; i < depth; i++, dim *= 3);

	for (i = 0; i < dim; i++) {
		for (j = 0; j < dim; j++) {
			for (d = dim / 3; d; d /= 3)
				if ((i % (d * 3)) / d == 1 && (j % (d * 3)) / d == 1)
					break;
			printf(d ? "  " : "##");
		}
		printf("\n");
	}

	return 0;
}


C++: 


#include <cstdint>
#include <cstdlib>
#include <cstdio>

static constexpr int32_t bct_low_bits = 0x55555555;

static int32_t bct_decrement(int32_t v) {
    --v;            
    return v ^ (v & (v>>1) & bct_low_bits);     
}

int main (int argc, char *argv[])
{
    
    const int32_t n = (1 < argc) ? std::atoi(argv[1]) : 3;
    
    if (n < 0 || 9 < n) {                       
        std::printf("N out of range (use 0..9): %ld\n", long(n));
        return 1;
    }

    const int32_t size_bct = 1<<(n*2);          
    
    int32_t y = size_bct;
    do {                                        
        y = bct_decrement(y);                   
        int32_t x = size_bct;
        do {                                    
            x = bct_decrement(x);               
            
            std::putchar((x & y & bct_low_bits) ? ' ' : '#');
        } while (0 < x);
        std::putchar('\n');
    } while (0 < y);

    return 0;
}
Task: Sorting algorithms_Bogosort

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

bool is_sorted(int *a, int n)
{
  while ( --n >= 1 ) {
    if ( a[n] < a[n-1] ) return false;
  }
  return true;
}

void shuffle(int *a, int n)
{
  int i, t, r;
  for(i=0; i < n; i++) {
    t = a[i];
    r = rand() % n;
    a[i] = a[r];
    a[r] = t;
  }
}

void bogosort(int *a, int n)
{
  while ( !is_sorted(a, n) ) shuffle(a, n);
}

int main()
{
  int numbers[] = { 1, 10, 9,  7, 3, 0 };
  int i;

  bogosort(numbers, 6);
  for (i=0; i < 6; i++) printf("%d ", numbers[i]);
  printf("\n");
}


C++: #include <algorithm>
#include <iostream>
#include <iterator>
#include <random>

template <typename RandomAccessIterator, typename Predicate>
void bogo_sort(RandomAccessIterator begin, RandomAccessIterator end,
               Predicate p) {
  std::random_device rd;
  std::mt19937 generator(rd());
  while (!std::is_sorted(begin, end, p)) {
    std::shuffle(begin, end, generator);
  }
}

template <typename RandomAccessIterator>
void bogo_sort(RandomAccessIterator begin, RandomAccessIterator end) {
  bogo_sort(
      begin, end,
      std::less<
          typename std::iterator_traits<RandomAccessIterator>::value_type>());
}

int main() {
  int a[] = {100, 2, 56, 200, -52, 3, 99, 33, 177, -199};
  bogo_sort(std::begin(a), std::end(a));
  copy(std::begin(a), std::end(a), std::ostream_iterator<int>(std::cout, " "));
  std::cout << "\n";
}
Task: Merge and aggregate datasets

C: 
#include <ctime>
#include <cstdint>
extern "C" {
  int64_t from date(const char* string) {
    struct tm tmInfo = {0};
    strptime(string, "%Y-%m-%d", &tmInfo);
    return mktime(&tmInfo); 
  }
}


C++: #include <iostream>
#include <optional>
#include <ranges>
#include <string>
#include <vector>

using namespace std;

struct Patient
{
    string ID;
    string LastName;
};

struct Visit
{
    string PatientID;
    string Date;
    optional<float> Score;
};

int main(void) 
{
    auto patients = vector<Patient> {
        {"1001", "Hopper"},
        {"4004", "Wirth"},
        {"3003", "Kemeny"},
        {"2002", "Gosling"},
        {"5005", "Kurtz"}};

    auto visits = vector<Visit> {    
        {"2002", "2020-09-10", 6.8},
        {"1001", "2020-09-17", 5.5},
        {"4004", "2020-09-24", 8.4},
        {"2002", "2020-10-08", },
        {"1001", ""          , 6.6},
        {"3003", "2020-11-12", },
        {"4004", "2020-11-05", 7.0},
        {"1001", "2020-11-19", 5.3}};

    
    sort(patients.begin(), patients.end(), 
         [](const auto& a, const auto&b){ return a.ID < b.ID;});    

    cout << "| PATIENT_ID | LASTNAME | LAST_VISIT | SCORE_SUM | SCORE_AVG |\n";
    for(const auto& patient : patients)
    {
        
        string lastVisit;
        float sum = 0;
        int numScores = 0;
        
        
        auto patientFilter = [&patient](const Visit &v){return v.PatientID == patient.ID;};
        for(const auto& visit : visits | views::filter( patientFilter ))
        {
            if(visit.Score)
            {
                sum += *visit.Score;
                numScores++;
            }
            lastVisit = max(lastVisit, visit.Date);
        }
        
        
        cout << "|       " << patient.ID << " | ";
        cout.width(8); cout << patient.LastName << " | ";
        cout.width(10); cout << lastVisit << " | ";
        if(numScores > 0)
        {
            cout.width(9); cout << sum << " | ";
            cout.width(9); cout << (sum / float(numScores));
        }
        else cout << "          |          ";
        cout << " |\n";
    }
}
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;
}


C++: #include <iomanip>
#include <iostream>

typedef double F(double,double);


void euler(F f, double y0, double a, double b, double h)
{
    double y = y0;
    for (double t = a; t < b; t += h)
    {
        std::cout << std::fixed << std::setprecision(3) << t << " " << y << "\n";
        y += h * f(t, y);
    }
    std::cout << "done\n";
}


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

int main()
{
    euler(newtonCoolingLaw, 100, 0, 100,  2);
    euler(newtonCoolingLaw, 100, 0, 100,  5);
    euler(newtonCoolingLaw, 100, 0, 100, 10);
}
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;
}


C++: #include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <boost/bind.hpp>
#include <iterator>

double nextNumber( double number ) {
   return number + floor( 0.5 + sqrt( number ) ) ;
}

int main( ) {
   std::vector<double> non_squares ;
   typedef std::vector<double>::iterator SVI ;
   non_squares.reserve( 1000000 ) ;   
   
   for ( double i = 1.0 ; i < 100001.0 ; i += 1 )
      non_squares.push_back( nextNumber( i ) ) ;  
   
   std::copy( non_squares.begin( ) , non_squares.begin( ) + 22 ,
	 std::ostream_iterator<double>(std::cout, " " ) ) ;     
   std::cout << '\n' ;
   
   SVI found = std::find_if ( non_squares.begin( ) , non_squares.end( ) ,
	 boost::bind( &floor, boost::bind( &sqrt, _1 ) ) == boost::bind( &sqrt, _1 ) ) ;
   if ( found != non_squares.end( ) ) {
      std::cout << "Found a square number in the sequence!\n" ;
      std::cout << "It is " << *found << " !\n" ;
   }
   else {
      std::cout << "Up to 1000000, found no square number in the sequence!\n" ;
   }
   return 0 ;
}
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;
}


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

int main()
{
  std::string s = "0123456789";

  int const n = 3;
  int const m = 4;
  char const c = '2';
  std::string const sub = "456";

  std::cout << s.substr(n, m)<< "\n";
  std::cout << s.substr(n) << "\n";
  std::cout << s.substr(0, s.size()-1) << "\n";
  std::cout << s.substr(s.find(c), m) << "\n";
  std::cout << s.substr(s.find(sub), m) << "\n";
}
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;



}


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

class jortSort {
public:
    template<class T>
    bool jort_sort( T* o, size_t s ) {
        T* n = copy_array( o, s );
        sort_array( n, s );
        bool r = false;

        if( n ) {
            r = check( o, n, s );
            delete [] n;
        }
        return r;
    }

private:
    template<class T>
    T* copy_array( T* o, size_t s ) {
        T* z = new T[s];
        memcpy( z, o, s * sizeof( T ) );
        
        return z;
    }
    template<class T>
    void sort_array( T* n, size_t s ) {
        std::sort( n, n + s );
    }
    template<class T>
    bool check( T* n, T* o, size_t s ) {
        for( size_t x = 0; x < s; x++ )
            if( n[x] != o[x] ) return false;
        return true;
    }
};

jortSort js;

template<class T>
void displayTest( T* o, size_t s ) {
    std::copy( o, o + s, std::ostream_iterator<T>( std::cout, " " ) );
    std::cout << ": -> The array is " << ( js.jort_sort( o, s ) ? "sorted!" : "not sorted!" ) << "\n\n";
}

int main( int argc, char* argv[] ) {
    const size_t s = 5;
    std::string oStr[] = { "5", "A", "D", "R", "S" };
    displayTest( oStr, s );
    std::swap( oStr[0], oStr[1] );
    displayTest( oStr, s );

    int oInt[] = { 1, 2, 3, 4, 5 };
    displayTest( oInt, s );
    std::swap( oInt[0], oInt[1] );
    displayTest( oInt, s );

    return 0;
}
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;
}


C++: #include <iostream>

bool is_leap_year(int year) {
  return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
}

int main() {
  for (auto year : {1900, 1994, 1996, 1997, 2000}) {
    std::cout << year << (is_leap_year(year) ? " is" : " is not") << " a leap year.\n";
  }
}
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;
}


C++: #include <boost/multiprecision/gmp.hpp>
#include <iostream>

using namespace boost::multiprecision;

mpz_int p(uint n, uint p) {
    mpz_int r = 1;
    mpz_int k = n - p;
    while (n > k)
        r *= n--;
    return r;
}

mpz_int c(uint n, uint k) {
    mpz_int r = p(n, k);
    while (k)
        r /= k--;
    return r;
}

int main() {
    for (uint i = 1u; i < 12u; i++)
        std::cout << "P(12," << i << ") = " << p(12u, i) << std::endl;
    for (uint i = 10u; i < 60u; i += 10u)
        std::cout << "C(60," << i << ") = " << c(60u, i) << std::endl;

    return 0;
}
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;
}


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

void lexicographical_sort(std::vector<int>& numbers) {
    std::vector<std::string> strings(numbers.size());
    std::transform(numbers.begin(), numbers.end(), strings.begin(),
                   [](int i) { return std::to_string(i); });
    std::sort(strings.begin(), strings.end());
    std::transform(strings.begin(), strings.end(), numbers.begin(),
                   [](const std::string& s) { return std::stoi(s); });
}

std::vector<int> lexicographically_sorted_vector(int n) {
    std::vector<int> numbers(n >= 1 ? n : 2 - n);
    std::iota(numbers.begin(), numbers.end(), std::min(1, n));
    lexicographical_sort(numbers);
    return numbers;
}

template <typename T>
void print_vector(std::ostream& out, const std::vector<T>& v) {
    out << '[';
    if (!v.empty()) {
        auto i = v.begin();
        out << *i++;
        for (; i != v.end(); ++i)
            out << ',' << *i;
    }
    out << "]\n";
}

int main(int argc, char** argv) {
    for (int i : { 0, 5, 13, 21, -22 }) {
        std::cout << i << ": ";
        print_vector(std::cout, lexicographically_sorted_vector(i));
    }
    return 0;
}
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;
}


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

using namespace std;

bool cmp(const string& a, const string& b)
{
    return b.length() < a.length(); 
}

void compareAndReportStringsLength(list<string> listOfStrings)
{
    if (!listOfStrings.empty())
    {
        char Q = '"';
        string has_length(" has length ");
        string predicate_max(" and is the longest string");
        string predicate_min(" and is the shortest string");
        string predicate_ave(" and is neither the longest nor the shortest string");

        list<string> ls(listOfStrings); 
        ls.sort(cmp);
        int max = ls.front().length();
        int min = ls.back().length();

        for (list<string>::iterator s = ls.begin(); s != ls.end(); s++)
        {
            int length = s->length();
            string* predicate;
            if (length == max)
                predicate = &predicate_max;
            else if (length == min)
                predicate = &predicate_min;
            else
                predicate = &predicate_ave;

            cout << Q << *s << Q << has_length << length << *predicate << endl;
        }
    }
}

int main(int argc, char* argv[])
{
    list<string> listOfStrings{ "abcd", "123456789", "abcdef", "1234567" };
    compareAndReportStringsLength(listOfStrings);

    return EXIT_SUCCESS;
}
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;
}


C++: #include <time.h>
#include <iostream>


using namespace std;


const int MAX = 126;
class shell
{
public:
    shell() 
    { _gap[0] = 1750; _gap[1] = 701; _gap[2] = 301; _gap[3] = 132; _gap[4] = 57; _gap[5] = 23; _gap[6] = 10; _gap[7] = 4; _gap[8] = 1; }

    void sort( int* a, int count )
    {
	_cnt = count;
	for( int x = 0; x < 9; x++ )
	    if( count > _gap[x] )
	    { _idx = x; break; }

	sortIt( a );
    }

private:	
    void sortIt( int* arr )
    {
	bool sorted = false;
	while( true )
	{
	    sorted = true;
	    int st = 0;
	    for( int x = _gap[_idx]; x < _cnt; x += _gap[_idx] )
	    {
		if( arr[st] > arr[x] )
		{ swap( arr[st], arr[x] ); sorted = false; }
		st = x;
	    }
	    if( ++_idx >= 8 ) _idx = 8;
	    if( sorted && _idx == 8 ) break;
	}
    }

    void swap( int& a, int& b ) { int t = a; a = b; b = t; }

    int _gap[9], _idx, _cnt;
};

int main( int argc, char* argv[] )
{
    srand( static_cast<unsigned int>( time( NULL ) ) ); int arr[MAX];
    for( int x = 0; x < MAX; x++ )
	arr[x] = rand() % MAX - rand() % MAX;

    cout << " Before: \n=========\n";
    for( int x = 0; x < 7; x++ )
    {
	for( int a = 0; a < 18; a++ )
	{ cout << arr[x * 18 + a] << " "; }
	cout << endl;
    }
    cout << endl; shell s; s.sort( arr, MAX );
	
    cout << " After: \n========\n";
    for( int x = 0; x < 7; x++ )
    {
	for( int a = 0; a < 18; a++ )
	{ cout << arr[x * 18 + a] << " "; }
	cout << endl;
    }
    cout << endl << endl; return system( "pause" );
}
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;
}


C++: #include <iostream>
#include <list>

int main ()
{
    std::list<int> numbers {1, 5, 7, 0, 3, 2};
    numbers.insert(numbers.begin(), 9); 
    numbers.insert(numbers.end(), 4); 
    auto it = std::next(numbers.begin(), numbers.size() / 2); 
    numbers.insert(it, 6); 
    for(const auto& i: numbers)
        std::cout << i << ' ';
    std::cout << '\n';
}
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']++;
}


C++: #include <fstream>
#include <iostream>

int main()
{
	std::ifstream input("filename.txt", std::ios_base::binary);
	if (!input)
	{
		std::cerr << "error: can't open file\n";
		return -1;
	}

	size_t count[256];
	std::fill_n(count, 256, 0);

	for (char c; input.get(c); ++count[uint8_t(c)]) 
		; 

	for (size_t i = 0; i < 256; ++i)
	{
		if (count[i] && isgraph(i)) 
		{
			std::cout << char(i) << " = " << count[i] << '\n';
		}
	}
}