Latest comments for language 'C++' on doukaku.org

mattsan's comment on 島の数をカウントする

おまけにこまかいミスがちらほら。とほほ orz。

#include <iostream>

static const int Width  = 4;
static const int Height = 4;

void markCell(int row, int col, const char cells[Height][Width], bool marks[Height][Width])
{
    marks[row][col] = true;
    if((row > 0         ) && ( ! marks[row - 1][col]) && (cells[row][col] == cells[row - 1][col])) markCell(row - 1, col, cells, marks);
    if((row < Height - 1) && ( ! marks[row + 1][col]) && (cells[row][col] == cells[row + 1][col])) markCell(row + 1, col, cells, marks);
    if((col > 0)          && ( ! marks[row][col - 1]) && (cells[row][col] == cells[row][col - 1])) markCell(row, col - 1, cells, marks);
    if((col < Width - 1)  && ( ! marks[row][col + 1]) && (cells[row][col] == cells[row][col + 1])) markCell(row, col + 1, cells, marks);
}

void doukaku219(const char cells[Height][Width])
{
    int  countWhite = 0;
    int  countBlack = 0;
    bool marks[Height][Width];

    for(int row = 0; row < Height; ++row)
    {
        for(int col = 0; col < Width; ++col)
        {
            marks[row][col] = 0;
        }
    }

    for(int row = 0; row < Height; ++row)
    {
        for(int col = 0; col < Width; ++col)
        {
            if( ! marks[row][col])
            {
                if(cells[row][col] == 0)
                {
                    ++countWhite;
                }
                else
                {
                    ++countBlack;
                }
                markCell(row, col, cells, marks);
            }
        }
    }

    std::cout << "白の島は" << countWhite << "つ" << std::endl;
    std::cout << "黒の島は" << countBlack << "つ" << std::endl;
}

int main(int, char* [])
{
    const char problem0[Width][Height] =
    {
        { 0, 1, 1, 0 },
        { 0, 0, 1, 0 },
        { 0, 1, 0, 0 },
        { 0, 1, 1, 0 }
    };

    const char problem1[Width][Height] =
    {
        { 0, 0, 0, 0 },
        { 1, 0, 1, 0 },
        { 0, 1, 0, 0 },
        { 0, 0, 0, 0 } 
    };

    doukaku219(problem0);
    doukaku219(problem1);

    return 0;
}

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匿名's comment on 島の数をカウントする

島の数をカウントする (Nested Flatten)

実質C言語ですね。
C++らしいのも考えたい…。

#include <iostream>

static const int Width  = 4;
static const int Height = 4;

void markCell(int row, int col, const char cells[Height][Width], bool marks[Height][Width])
{
    marks[row][col] = true;
    if((row > 0         ) && ( ! marks[row - 1][col]) && (cells[row][col] == cells[row - 1][col])) markCell(row - 1, col, cells, marks);
    if((row < Height - 1) && ( ! marks[row + 1][col]) && (cells[row][col] == cells[row + 1][col])) markCell(row + 1, col, cells, marks);
    if((col > 0)          && ( ! marks[row][col - 1]) && (cells[row][col] == cells[row][col - 1])) markCell(row, col - 1, cells, marks);
    if((col < Width - 1)  && ( ! marks[row][col + 1]) && (cells[row][col] == cells[row][col + 1])) markCell(row, col + 1, cells, marks);
}

void doukaku219(const char cells[Height][Width])
{
    int  countWhite = 0;
    int  countBlack = 0;
    bool marks[Height][Width];

    for(int row = 0; row < Height; ++row)
    {
        for(int col = 0; col < Width; ++col)
        {
            marks[row][col] = 0;
        }
    }

    for(int row = 0; row < Height; ++row)
    {
        for(int col = 0; col < Width; ++col)
        {
            if( ! marks[row][col])
            {
                if(cells[row][col] == 0)
                {
                    ++countWhite;
                }
                else
                {
                    ++countBlack;
                }
                marks[row][col] = true;
            }
            markCell(row, col, cells, marks);
        }
    }

    std::cout << "白の島は" << countWhite << "つ" << std::endl;
    std::cout << "黒の島は" << countBlack << "つ" << std::endl;
}

int main(int, char* [])
{
    const char probrem0[Width][Height] =
    {
        { 0, 1, 1, 0 },
        { 0, 0, 1, 0 },
        { 0, 1, 0, 0 },
        { 0, 1, 1, 0 }
    };

    const char probrem1[Width][Height] =
    {
        { 0, 0, 0, 0 },
        { 1, 0, 1, 0 },
        { 0, 1, 0, 0 },
        { 0, 0, 0, 0 } 
    };

    doukaku219(probrem0);
    doukaku219(probrem1);

    return 0;
}

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匿名's comment on 小町算

小町算 (Nested Flatten)

別にintでいいところまでdoubleにしてました。やりなおし。

#include <cstdio>
#include <cmath>

const int EXPRSIZ = 17;
enum { _ = -5, ADD, SUB, MUL, DIV };
const int operators[] = { _, ADD, SUB, MUL, DIV };

int priority(int op)
{
    switch (op) {
        case _: return 3;
        case ADD: case SUB: return 1;
        default: return 2;
    }
}
void torpn(const int *expr, int *rpn)
{
    int stack[EXPRSIZ];
    int sp = 0;
    for (int i = 0; i < EXPRSIZ; ++i) {
        if (expr[i] > 0) *rpn++ = expr[i];
        else {
            int pri = priority(expr[i]);
            if (!sp || pri > priority(stack[sp-1]))
                stack[sp++] = expr[i];
            else {
                do *rpn++ = stack[--sp];
                while (sp > 0 && pri <= priority(stack[sp-1]));
                stack[sp++] = expr[i];
            }
        }
    }
    while (sp > 0) *rpn++ = stack[--sp];
}
double eval(const int *rpn)
{
    double stack[EXPRSIZ];
    int sp = 0;
    for (int i = 0; i < EXPRSIZ; ++i) {
        if (rpn[i] > 0) stack[sp++] = static_cast<double>(rpn[i]);
        else {
            double y = stack[--sp], x = stack[--sp];
            switch (rpn[i]) {
                case _: stack[sp++] = x * 10 + y; break;
                case ADD: stack[sp++] = x + y; break;
                case SUB: stack[sp++] = x - y; break;
                case MUL: stack[sp++] = x * y; break;
                case DIV: stack[sp++] = x / y; break;
            }
        }
    }
    return stack[sp-1];
}
void print(const int *expr)
{
    for (int i = 0; i < EXPRSIZ; ++i)
        if (expr[i] > 0)
            std::printf("%d", expr[i]);
        else if (expr[i] != _)
            std::printf(" %c ", "+-*/"[expr[i] + 4]);
    std::putchar('\n');
}
int main()
{
    int expr[] = { 1, 0, 2, 0, 3, 0, 4, 0, 5, 0, 6, 0, 7, 0, 8, 0, 9 };
    int rpn[EXPRSIZ], limit = static_cast<int>(std::pow(5.,8.));
    for (int i = 0; i < limit; ++i) {
        for (int n = i, j = 0; j < 8; ++j, n /= 5)
            expr[2 * j + 1] = operators[n % 5];
        torpn(expr, rpn);
        if (eval(rpn) == 100.) print(expr);
    }
}

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匿名's comment on 小町算

小町算 (Nested Flatten)

C++ですがCみたいなコードになってしまいました

#include <cstdio>
#include <cmath>

const int EXPRSIZ = 17;
enum { _ = -5, ADD, SUB, MUL, DIV };
const int operators[] = { _, ADD, SUB, MUL, DIV };

int priority(double op)
{
    switch (static_cast<int>(op)) {
        case _: return 3;
        case ADD: case SUB: return 1;
        default: return 2;
    }
}
void torpn(const double *expr, double *rpn)
{
    double stack[EXPRSIZ];
    int sp = 0;
    for (const double *endp = expr + EXPRSIZ; expr != endp; ++expr) {
        if (*expr > 0) *rpn++ = *expr;
        else {
            int pri = priority(*expr);
            if (!sp || pri > priority(stack[sp-1])) stack[sp++] = *expr;
            else {
                do *rpn++ = stack[--sp];
                while (sp > 0 && pri <= priority(stack[sp-1]));
                stack[sp++] = *expr;
            }
        }
    }
    while (sp > 0) *rpn++ = stack[--sp];
}
double eval(const double *rpn)
{
    double stack[EXPRSIZ];
    int sp = 0;
    for (const double *endp = rpn + EXPRSIZ; rpn < endp; ++rpn) {
        if (*rpn > 0) stack[sp++] = *rpn;
        else {
            double y = stack[--sp], x = stack[--sp];
            switch (static_cast<int>(*rpn)) {
                case _: stack[sp++] = x * 10 + y; break;
                case ADD: stack[sp++] = x + y; break;
                case SUB: stack[sp++] = x - y; break;
                case MUL: stack[sp++] = x * y; break;
                case DIV: stack[sp++] = x / y; break;
            }
        }
    }
    return stack[sp-1];
}
void print(double *expr)
{
    for (int i = 0; i < EXPRSIZ; ++i)
        if (expr[i] > 0)
            std::printf("%g", expr[i]);
        else if (expr[i] != _)
            std::printf(" %c ", "+-*/"[static_cast<int>(expr[i]) + 4]);
    std::putchar('\n');
}
int main()
{
    double expr[] = { 1., 0., 2., 0., 3., 0., 4., 0., 5.,
                        0., 6., 0., 7., 0., 8., 0., 9. };
    double rpn[EXPRSIZ], stack[EXPRSIZ];
    for (int i = 0, limit = static_cast<int>(std::pow(5., 8.)); i < limit; ++i) {
        for (int n = i, j = 0; j < 8; ++j, n /= 5)
            expr[2 * j + 1] = operators[n % 5];
        torpn(expr, rpn);
        if (eval(rpn) == 100.0) print(expr);
    }
}

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vtwntmtn's comment on 疑似並行処理

疑似並行処理 (Nested Flatten)

考慮しました。

#include <string>
#include <cstdlib>
#include <iostream>

#include <boost/thread.hpp>

class Proc
{
private:
    std::string m_str;
    boost::mutex & m_mtx;

public:
    Proc(std::string s, boost::mutex & m) : m_str(s), m_mtx(m) {}
    
    void operator () (void)
    {
        for (int i = 0; i < m_str.size(); ++i)
        {
            usleep(1);
            boost::mutex::scoped_lock lck(m_mtx);
            std::cout << m_str[i] << std::flush;
        }
    }
};

int main(void)
{
    boost::mutex mutex;
    boost::thread numbers(Proc("0123456789", mutex));
    boost::thread alphabets(Proc("ABCDEFGHIJ", mutex));
    numbers.join();
    alphabets.join();
    return 0;
}

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vtwntmtn's comment on 疑似並行処理

疑似並行処理 (Nested Flatten)

boost::thread版です。g++の場合は以下のようにコンパイルしてください。

g++ para.cxx -lboost_thread

#include <string>
#include <iostream>

#include <boost/thread/thread.hpp>

class Proc
{
private:
    std::string m_str;

public:
    Proc(std::string s) : m_str(s) {}
    
    void operator () (void)
    {
        for (int i = 0; i < m_str.size(); ++i)
        {
            std::cout << m_str[i] << std::flush;
        }
    }
};

int main(void)
{
    Proc numbers("0123456789");
    Proc alphabets("ABCDEFGHIJ");
    boost::thread nt(numbers);
    boost::thread at(alphabets);
    nt.join();
    at.join();
    return 0;
}

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Y's comment on 疑似並行処理

疑似並行処理 (Nested Flatten)

OpenMPを使います。

gcc 4.2以上なら-fopenmp、iccなら-openmpというコンパイラオプションを付けます。
Visual C++ならオプションでOpenMPを有効にます。

結果：
1 A 2 B 3 C 4 D 5 E 6 F 7 G 8 H 9 I 10 J

#include <iostream>
#include <string>
using namespace std;

void funcA() {
  for (int i=1; i<=10; ++i) {
    #pragma omp critical
    cout<<i<<' ';
  }
}

void funcB() {
  string s="ABCDEFGHIJ";
  for (size_t i=0; i<s.length(); ++i) {
    #pragma omp critical
    cout<<s.at(i)<<' ';
  }
}

int main() {
  #pragma omp parallel num_threads(2)
  {
    #pragma omp sections
    {
      #pragma omp section
      funcA();
      #pragma omp section
      funcB();
    }
  }
}

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egtra's comment on リストを逆順に表示

リストを逆順に表示 (Nested Flatten)

Boost 1.36には逆順foreachが追加されました。それを使うと、こう書けます。

<algorithm>などの関数でかけるならそっちのほうが私の好みですが。

#include <iostream>
#include <boost/foreach.hpp>

int main()
{
    static const int a[] = {1, 2, 3, 4, 5};
    BOOST_REVERSE_FOREACH(int i, a)
    {
        std::cout << i << '\n';
    }
    std::cout << std::flush;
}

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