Problem 07 - Ch 06

src/com/deepak/ctci/Ch06_Math_And_Logic_Puzzles/Problem_07.java

@@ -4,6 +4,8 @@
  */
 package com.deepak.ctci.Ch06_Math_And_Logic_Puzzles;
 
+import java.util.Random;
+
 /**
  * <br> Problem Statement :
  * 
@@ -12,7 +14,7 @@
  * families should ensure that they have one girl or else they face 
  * massive fines. If all families abide by this policy, that is, 
  * they continue to have children until they have one girl, 
- * at which point they immediately stop what will the gender ratio 
+ * at which point they immediately stop. What will the gender ratio 
  * of the new generation be?. Assume that the odds of someone having 
  * a boy or girl is equal. Solve this logically then write a simulation of it.
  *  
@@ -21,5 +23,58 @@
  * @author Deepak
  */
 public class Problem_07 {
-
+
+	/**
+	 * There are no unit tests for this because, every time
+	 * ratio will be different since random generation is
+	 * involved here
+	 * 
+	 * @param args
+	 */
+	public static void main(String[] args) {
+		System.out.println("Ration for Girls v/s Boys => " + runFamilies(100) * 100);
+	}
+
+	/**
+	 * Method to run the logic on n number of families
+	 * 
+	 * @param numberOfFamilies
+	 * @return {@link double}
+	 */
+	public static double runFamilies(int numberOfFamilies) {
+		int boys = 0;
+		int girls = 0;
+		/* Find the genders for each family and calculate percentage */
+		for (int i = 0; i < numberOfFamilies; i++) {
+			int[] genders = runOneFamily();
+			boys += genders[0];
+			girls += genders[1];
+		}
+		return girls / (double) (boys + girls);
+	}
+
+	/**
+	 * Method to run one family
+	 * 
+	 * @return {@link int[]}
+	 */
+	public static int[] runOneFamily() {
+		int boys = 0;
+		int girls = 0;
+		Random random = new Random();
+		/* Keep going until girl child is born */
+		while (girls == 0) {
+			/* If true, it's a boy else a girl */
+			boolean nextChild = random.nextBoolean();
+			if (nextChild) {
+				boys++;
+			} else {
+				girls++;
+			}
+		}
+		/* Create an integer for count of both */
+		int[] genders = {boys, girls};
+		return genders;
+	}
+
 }