Collision pi

#include "stdafx.h"
#include <iostream>

// 碰撞后速度
void txpz(double m1, double m2, double & v1,  double & v2)
{
	double v1_ = ((m1-m2)* v1 + 2 * m2 * v2) / (m1 + m2);
	double v2_ = ((m2-m1) * v2 + 2 * m1 * v1) / (m1 +m2);

	v1 = v1_;
	v2 = v2_;
}

// 完全弹性碰撞( 返回碰撞次数 )
int cishu(double m1, double m2) 
{
	double v1 = -1.0;
	double v2 = 0;
	int nTime = 0;
	while (true) {
		if ((v1 >= 0) && (v2 < v1)) 
		{
			break;
		}

		txpz(m1, m2, v1, v2);
		nTime ++;

		if (v2 < 0)
		{
			v2 = -v2;
			nTime ++;
		}
	}
	using namespace std;
	cout<<m1<< "\t"<<m2<< "\t"<< nTime<<endl;
	return nTime;
}

int main()
{
	for (int i = 1; i < 8; i ++)
	{
		cishu(pow(100,i) * 1.0, 1.0);
	}
	
    return 0;
}

Take a look at an interesting code

// Put another LUA version below

function txpz(t)
    local m1 = t.m1
    local m2 = t.m2
    local v1 = t.v1
    local v2 = t.v2

	t.v1 = ((m1-m2) * v1 + 2 * m2 * v2) / (m1 + m2);
	t.v2 = ((m2-m1) * v2 + 2 * m1 * v1) / (m1 + m2);
end

function cishu(t)
	t.v1 = -1.0;
	t.v2 = 0;
	local nTime = 0;
	while true do
		if t.v1 >= 0 and t.v2 < t.v1 then
			break;
        end

		txpz(t);
		nTime = nTime + 1;

		if t.v2 < 0 then
			t.v2 = -t.v2;
            nTime = nTime + 1;
        end
	end
	return nTime;
end

print(cishu{m1 = 1.0, m2 = 1.0})
print(cishu{m1 = 100.0, m2 = 1.0})
print(cishu{m1 = 10000.0, m2 = 1.0})
print(cishu{m1 = 1000000.0, m2 = 1.0})
print(cishu{m1 = 100000000.0, m2 = 1.0})
print(cishu{m1 = 100000000.0, m2 = 0.01})
print(cishu{m1 = 100000000.0, m2 = 0.0001})
print(cishu{m1 = 100000000.0, m2 = 0.000001})