Question

我在C ++中阅读了有关skipList实现的内容，我不理解这个随机函数：

float frand() {
    return (float) rand() / RAND_MAX;
}
int random_level() {
    static bool first = true;

    if (first) {
        srand( (unsigned)time(NULL) );
        first = false;
    }

    int lvl = (int)(log(frand())/log(1.-P));
    return lvl < MAX_LEVEL ? lvl : MAX_LEVEL;
}

感谢阅读，我在等你的回答：）

Answer 1

因此，跳过列表的工作方式是使新节点在级别上链接到其他节点，随机选择是否添加级别。通常，这意味着为新节点要链接的每个级别翻转一次硬币。如果它出现在头部，你会上升一个水平并再次翻转，如果是尾巴，你就完成了。

它的作用是模拟硬币翻转几次，但只调用一次随机数源，并应用具有相同概率分布的函数作为连续硬币翻转的总和

Answer 2

  // this function generates a random number between 0 and 1
float frand() {
    return (float) rand() / RAND_MAX;  // RAND_MAX is the biggest possible value returned by rand()
}
int random_level() {
    static bool first = true;   // a static variable to track whether or not this is the first run of the function

    if (first) {  // if this is the first time the function has been called...
        srand( (unsigned)time(NULL) );    // generate a seed from the current time
        first = false; // set first to false
    }

    int lvl = (int)(log(frand())/log(1.-P));  // generate the value of lvl with some weird log functions
    return lvl < MAX_LEVEL ? lvl : MAX_LEVEL;  // cap the value to MAX_LEVEL, and return
}

Skiplast随机函数需要解释

2 个答案: