数据结构中的几何分布
几何分布是n=0、1、2，...的离散概率分布。具有概率密度函数。
$$P\lgroupn\rgroup=p\lgroup1-p\rgroup^{n}$$
分布函数为-
$$D\lgroupn\rgroup=\displaystyle\sum\limits_{i=0}^nP\lgroupi\rgroup=1-q^{n+1}$$
示例
#include <iostream>
#include <random>
using namespace std;
int main(){
const int nrolls = 10000; // number of rolls
const int nstars = 100; // maximum number of stars to distribute
default_random_engine generator;
geometric_distribution<int> distribution(0.3);
int p[10]={};
for (int i=0; i<nrolls; ++i) {
int number = distribution(generator);
if (number<10)
p[number]++;
}
cout << "Geometric_distribution (0.3):" << endl;
for (int i=0; i<10; ++i)
cout << i << ": " << string(p[i]*nstars/nrolls,'*') << endl;
}输出结果
0: ***************************** 1: ******************** 2: *************** 3: ********** 4: ******* 5: **** 6: *** 7: ** 8: * 9: *