Algorithm for obtaining random numbers with the same probability

In the past few days, when I started a lottery program at the annual meeting of the company, I thought the algorithm was very simple. I put the employee data into the list and used the list label as the random number to be obtained, based on the random number, the winner is determined. Later tests showed that the random number distribution was very uneven. It was later known that the random numbers obtained by the computer were all pseudo-random numbers. When the lottery was very fast, the random numbers obtained were very uneven. Therefore, a delay was required for each lottery. Later, the algorithm was re-designed and finally implemented. The algorithm principle is similar to the binary search process. A coin has the same positive probability and negative probability. When the number of samples increases infinitely, the probability of sampling is 50%. The Code is as follows: copy the code public partial class MainWindow: Window {string s; int number; public MainWindow () {InitializeComponent ();} public int getRandom () {// string [] arr = new string [5] {"", "yes", "1", "", "team "}; random r = new Random (); int num = 2; int choose = r. next (num); return choose; // MessageBox. show (arr [choose]. toString ();} public string GRandom (int n) {// if () if (n = 0) {// s = getRandom () + s; // System. threading. thread. sleep (1); return s;} if (n % 2 = 0) {n = n/2;} else {n = (n-1)/2; // s = getRandom () + s;} s = getRandom () + s; System. threading. thread. sleep (20); GRandom (n); // System. threading. thread. sleep (1); return s;} public Int32 Estimate (int n) {string num = GRandom (n); number = Convert. toInt32 (num, 2); if (number> n-1) {// num = ""; s = ""; Estimate (n );} // else return number;} private void Button_Click (object sender, RoutedEventArgs e) {for (int I = 0; I <100; I ++) {label1.Content + = Estimate (200) + ";"; s = "";}}}