ex 雙重支付攻擊成功機率

假設壞礦工的算力為4.3%，請問確認次數z幾次，可達雙重支付攻擊成功機率p< 0.0001




Hint:
#include <iostream>
#include <cmath>
using namespace std;

double AttackerSuccessProbability(double q, int z)
{
double p = 1.0 - q;
double lambda = z * (q / p);
double sum = 1.0;
int i, k;
for (k = 0; k <= z; k++)
{
double poisson = exp(-lambda);
for (i = 1; i <= k; i++)
poisson *= lambda / i;
sum -= poisson * (1 - pow(q / p, z - k));
}
return sum;
}