stl mt19937

`std::mt19937` 是 C++ 标准库中的一个伪随机数生成器。它是 Mersenne Twister 算法的一个实现，可以生成高质量的随机数序列。

您可以使用以下代码来使用 `std::mt19937`：

#include <iostream>
#include <random>

int main() {
    // 创建一个 mt19937 对象并初始化种子
    std::mt19937 rng(std::random_device{}());

    // 生成随机整数
    std::uniform_int_distribution<int> dist(1, 100);
    int random_number = dist(rng);

    std::cout << "随机数: " << random_number << std::endl;

    return 0;
}

在上面的示例中，我们首先创建了一个 `std::mt19937` 对象 `rng` 并通过 `std::random_device` 来初始化种子。然后，我们使用 `std::uniform_int_distribution` 来定义生成随机整数的范围，并使用 `dist(rng)` 来生成随机数。

希望这可以解答您的问题！如果您还有其他问题，请随时提问。

相关问题

mt19937的用法

在C++ STL中，可以通过 `<random>` 头文件中的 `mt19937` 类来实现MT19937算法的使用。

下面是一个简单的示例代码，演示如何生成一个随机数序列：

#include <random>
#include <iostream>

int main() {
    std::random_device rd;  // 获取一个随机设备
    std::mt19937 gen(rd()); // 使用随机设备生成种子值
    std::uniform_int_distribution<> distrib(1, 6); // 生成随机数分布

    for (int i = 0; i < 10; ++i) {
        std::cout << distrib(gen) << ' '; // 生成随机数并输出
    }

    return 0;
}

在这个示例代码中，我们首先使用 `std::random_device` 来获取一个随机设备，然后使用 `std::mt19937` 类来生成一个MT19937算法的随机数生成器，使用随机设备生成种子值。接下来，我们使用 `std::uniform_int_distribution` 类来生成一个在1到6之间均匀分布的随机数分布，并且通过随机数生成器来生成随机数。

在这个示例代码中，我们生成了10个1到6之间的随机数，并且将它们输出到屏幕上。你可以根据需要修改随机数的分布和生成的随机数个数。

#include <iostream>#include <random>#include <string>#include <algorithm>#include <cctype>using namespace std;const int MAX_WRONG = 6;const string WORDS[] = {"HELLO", "WORLD", "COMPUTER", "PROGRAMMING", "LANGUAGE"};const int NUM_WORDS = sizeof(WORDS) / sizeof(string);int main() { random_device rd; mt19937 gen(rd()); uniform_int_distribution<> dis(0, NUM_WORDS - 1); char playAgain = 'y'; while (tolower(playAgain) == 'y') { string word = WORDS[dis(gen)]; int wrongGuesses = 0; string guessedSoFar(word.size(), '_'); string lettersGuessed; cout << "Welcome to Hangman. Good luck!\n\n"; while (wrongGuesses < MAX_WRONG && guessedSoFar != word) { cout << "You have " << MAX_WRONG - wrongGuesses << " incorrect guesses left.\n"; cout << "You've used the following letters:\n" << lettersGuessed << endl; cout << "So far, the word is:\n" << guessedSoFar << endl; char guess; cout << "\nEnter your guess: "; cin >> guess; guess = toupper(guess); if (lettersGuessed.find(guess) != string::npos) { cout << "You've already guessed " << guess << endl; continue; } lettersGuessed += guess; if (word.find(guess) != string::npos) { cout << "That's right! " << guess << " is in the word.\n"; for (int i = 0; i < word.size(); ++i) { if (word[i] == guess) { guessedSoFar[i] = guess; } } } else { cout << "Sorry, " << guess << " isn't in the word.\n"; ++wrongGuesses; } } if (wrongGuesses == MAX_WRONG) { cout << "\nYou've been hanged!"; } else { cout << "\nYou guessed it!"; } cout << "\nThe word was " << word << endl; cout << "Do you want to play again? (y/n): "; cin >> playAgain; } return 0;}优化这段代码

以下是对这段代码的一些优化建议：

1. 对于随机数生成器的使用，可以将其封装成一个函数，减少代码重复。

2. 可以将常量 MAX_WRONG 和 WORDS[] 定义为 const 类型，避免被误修改。

3. 使用 range-based for 循环来遍历 lettersGuessed 字符串。

4. 可以将判断 guess 是否已经猜过的代码抽象成一个函数。

5. 对于字符串的查找和替换操作，可以使用 STL 中提供的相应函数，如 find() 和 replace()，而不是手动实现。

6. 对于输入的字符，可以先使用 cin.get() 获取一个字符，再使用 toupper() 函数将其转换成大写字母。

7. 可以将游戏逻辑封装成一个函数，提高代码复用性。

下面是优化后的代码：

#include <iostream>
#include <random>
#include <string>
#include <algorithm>
#include <cctype>

using namespace std;

const int MAX_WRONG = 6;
const string WORDS[] = {"HELLO", "WORLD", "COMPUTER", "PROGRAMMING", "LANGUAGE"};
const int NUM_WORDS = sizeof(WORDS) / sizeof(string);

// 生成随机数
int getRandomNumber(int min, int max) {
    random_device rd;
    mt19937 gen(rd());
    uniform_int_distribution<> dis(min, max);
    return dis(gen);
}

// 判断字符是否已经猜过
bool isGuessAlreadyMade(char guess, const string& lettersGuessed) {
    return (lettersGuessed.find(guess) != string::npos);
}

// 猜词游戏逻辑
void playGame() {
    string word = WORDS[getRandomNumber(0, NUM_WORDS - 1)];
    int wrongGuesses = 0;
    string guessedSoFar(word.size(), '_');
    string lettersGuessed;
    cout << "Welcome to Hangman. Good luck!\n\n";
    while (wrongGuesses < MAX_WRONG && guessedSoFar != word) {
        cout << "You have " << MAX_WRONG - wrongGuesses << " incorrect guesses left.\n";
        cout << "You've used the following letters:\n";
        for (char letter : lettersGuessed) {
            cout << letter << " ";
        }
        cout << endl;
        cout << "So far, the word is:\n" << guessedSoFar << endl;
        char guess;
        cout << "\nEnter your guess: ";
        cin.get(guess);
        guess = toupper(guess);
        if (isGuessAlreadyMade(guess, lettersGuessed)) {
            cout << "You've already guessed " << guess << endl;
            continue;
        }
        lettersGuessed += guess;
        if (word.find(guess) != string::npos) {
            cout << "That's right! " << guess << " is in the word.\n";
            replace(guessedSoFar.begin(), guessedSoFar.end(), '_', guess);
        } else {
            cout << "Sorry, " << guess << " isn't in the word.\n";
            ++wrongGuesses;
        }
    }
    if (wrongGuesses == MAX_WRONG) {
        cout << "\nYou've been hanged!";
    } else {
        cout << "\nYou guessed it!";
    }
    cout << "\nThe word was " << word << endl;
}

int main() {
    char playAgain = 'y';
    while (tolower(playAgain) == 'y') {
        playGame();
        cout << "Do you want to play again? (y/n): ";
        cin >> playAgain;
    }
    return 0;
}