功能：计算圆周率的近似值.

1.#include
2.#include
3.#include
4.using namespace std;
5.
6.int main()
7.{
8.const int MAX_TIMES = 200000000;
9.srand(static_cast(time(0)));
10.
11.int inside = 0;
12.for(int i = 0; i < MAX_TIMES; ++i) {
13.double x = static_cast(rand()) / RAND_MAX;
14.double y = static_cast(rand()) / RAND_MAX;
15.if(x * x + y * y