## Problem:

Working from left-to-right if no digit is exceeded by the digit to its left it is called an increasing number; for example, 134468.

Similarly if no digit is exceeded by the digit to its right it is called a decreasing number; for example, 66420.

We shall call a positive integer that is neither increasing nor decreasing a "bouncy" number; for example, 155349.

Clearly there cannot be any bouncy numbers below one-hundred, but just over half of the numbers below one-thousand (525) are bouncy. In fact, the least number for which the proportion of bouncy numbers first reaches 50% is 538.

Surprisingly, bouncy numbers become more and more common and by the time we reach 21780 the proportion of bouncy numbers is equal to 90%.

Find the least number for which the proportion of bouncy numbers is exactly 99%.

76576500

## Code:The solution may include methods that will be found here: Library.java .

public interface EulerSolution{public String run();}
/*  * Solution to Project Euler problem 12 * By Nayuki Minase *  * http://nayuki.eigenstate.org/page/project-euler-solutions * https://github.com/nayuki/Project-Euler-solutions */public final class p012 implements EulerSolution {		public static void main(String[] args) {		System.out.println(new p012().run());	}			public String run() {		int num = 0;		for (int i = 1; ; i++) {			num += i;  // num is triangle number i			if (countDivisors(num) > 500)				return Integer.toString(num);		}	}			private static int countDivisors(int n) {		int count = 0;		int end = Library.sqrt(n);		for (int i = 1; i < end; i++) {			if (n % i == 0)				count += 2;		}		if (end * end == n)  // Perfect square			count++;		return count;	}	}