Chapter 03 section 06 codes added.

Author: liuyubobobo

03-Probability-Simulation/05-Pi-Estimation-Without-Rendering/src/MonteCarloExperiment.java

@@ -5,7 +5,6 @@ public class MonteCarloExperiment {
     private int squareSide;
     private int N;
     private int outputInterval = 100;
-    MonteCarloPiData data;
 
     public MonteCarloExperiment(int squareSide, int N){
 
@@ -14,9 +13,6 @@ public MonteCarloExperiment(int squareSide, int N){
 
         this.squareSide = squareSide;
         this.N = N;
-
-        Circle circle = new Circle(squareSide/2, squareSide/2, squareSide/2);
-        data = new MonteCarloPiData(circle);
     }
 
     public void setOutputInterval(int interval){
@@ -29,6 +25,9 @@ public void setOutputInterval(int interval){
 
     public void run(){
 
+        Circle circle = new Circle(squareSide/2, squareSide/2, squareSide/2);
+        MonteCarloPiData data = new MonteCarloPiData(circle);
+
         for(int i = 0 ; i < N ; i ++){
 
             if( i % outputInterval == 0) {

03-Probability-Simulation/06-Three-Gates-Problem/src/ThreeGatesExperiment.java

@@ -0,0 +1,44 @@
+
+public class ThreeGatesExperiment {
+
+    private int N;
+
+    public ThreeGatesExperiment(int N){
+
+        if(N <= 0)
+            throw new IllegalArgumentException("N must be larger than 0!");
+
+        this.N = N;
+    }
+
+    public void run(boolean changeDoor){
+
+        int wins = 0;
+        for(int i = 0 ; i < N ; i ++)
+            if(play(changeDoor))
+                wins ++;
+        System.out.println(changeDoor ? "Change" : "Not Change");
+        System.out.println("win rate:" + (double)wins/N);
+    }
+
+    private boolean play(boolean changeDoor){
+
+        int prizeDoor = (int)(Math.random() * 3);
+        int playerChoice = (int)(Math.random() * 3);
+
+        if(playerChoice == prizeDoor)
+            return changeDoor ? false : true;
+        else
+            return changeDoor ? true : false;
+    }
+
+    public static void main(String[] args) {
+
+        int N = 1000000;
+        ThreeGatesExperiment exp = new ThreeGatesExperiment(N);
+
+        exp.run(true);
+        System.out.println();
+        exp.run(false);
+    }
+}