int HEADS = 0;
int TAILS = 1;
int numHeads = 0;
int numTails = 0;
float headsPercentage = 0;

void runTest(int n) {
  
  for (int i = 0; i < n; i++) {
    int coinFlip = (int) random(2);
    if (coinFlip == HEADS) 
      numHeads++;
     else 
       numTails++;
  }
  headsPercentage = (float) numHeads/(numHeads+numTails);
  println("Percentage of heads: " + headsPercentage);
}

void setup() {
  size(200, 200);
  runTest(1000000);
}