[your code here]

[Paul Backus]

On Tuesday, 27 April 2021 at 21:04:19 UTC, Jeff Pratt wrote:
> ```
> // Estimate π using random integers
> void main()
> {
>     import std.stdio, std.random, std.math, std.conv;
>     ulong gcd(ulong a, ulong b)
>     {
>         if (b == 0) return a;
>         return gcd(b, a % b);
>     }
>     Mt19937_64 gen; gen.seed(unpredictableSeed!ulong);
>     int pairCount = 1_000_000;
>     int coprimeCount = 0;
>     ulong a, b;
>     for (int i = 0; i < pairCount; i++) {
>         a = gen.front; gen.popFront();
>         b = gen.front; gen.popFront();
>         if (gcd(a, b) == 1) coprimeCount++;
>     }
>     double prob = coprimeCount.to!double / pairCount.to!double;
>     writefln("π ≈ %.15f", sqrt(6.0 / prob));
> }
> ```

Nice example! A couple small improvements:

* You can use `std.numeric.gcd` instead of writing your own.
* You can use a `foreach` loop instead of a `for` loop.

```
// Estimate π using random integers
void main()
{
     import std.stdio, std.random, std.math, std.conv, std.numeric;
     Mt19937_64 gen; gen.seed(unpredictableSeed!ulong);
     int pairCount = 1_000_000;
     int coprimeCount = 0;
     ulong a, b;
     foreach (int i; 0 .. pairCount) {
         a = gen.front; gen.popFront();
         b = gen.front; gen.popFront();
         if (gcd(a, b) == 1) coprimeCount++;
     }
     double prob = coprimeCount.to!double / pairCount.to!double;
     writefln("π ≈ %.15f", sqrt(6.0 / prob));
}
```