QuestionB.java

package Q16_10_Living_People;

import java.util.Random;

public class QuestionB {

	public static int maxAliveYear(Person[] people, int min, int max) {
		int[] years = createYearMap(people, min, max);
		int best = getMaxIndex(years);

		return best + min;
	}
	
	/* Add each person's years to a year map. */	
	public static int[] createYearMap(Person[] people, int min, int max) {
		int[] years = new int[max - min + 1];
		for (Person person : people) {
			int left = person.birth - min;
			int right = person.death - min;			
			incrementRange(years, left, right);
		}
		return years;
	}
	
	/* Increment array for each value between left and right. */
	public static void incrementRange(int[] values, int left, int right) {
		for (int i = left; i <= right; i++) {
			values[i]++;
		}
	}	
	
	/* Get index of largest element in array. */
	public static int getMaxIndex(int[] values) {
		int max = 0;
		for (int i = 1; i < values.length; i++) {
			if (values[i] > values[max]) {
				max = i;
			}
		}
		return max;
	}	
	
	public static void main(String[] args) {
		int n = 3;
		int first = 1900;
		int last = 2000;
		Random random = new Random();
		Person[] people = new Person[n];
		for (int i = 0; i < n; i++) {
			int birth = first + random.nextInt(last - first);
			int death = birth + random.nextInt(last - birth);
			people[i] = new Person(birth, death);
			System.out.println(birth + ", " + death);
		}
		int year = maxAliveYear(people, first, last);
		System.out.println(year);
	}

}