a Programmer's blog

Problem 42: The nth term of the sequence of triangle numbers is given by, tn = ½n(n+1);

Using this word list, convert each letter in a word to a number corresponding to its alphabetical position and adding these values we form a word value. For example, the word value for SKY is 19 + 11 + 25 = 55 = t10. If the word value is a triangle number then we shall call the word a triangle word.

How many are triangle words?

import java.util.Vector;

class runner
{
	private static boolean isTriangle(int sum, Vector triangle){
		int last = triangle.lastElement();
		while(last < sum){
			last = triangle.size()*(triangle.size()+1)/2;
			triangle.add(last);
		}


		for(int x : triangle){
			if(sum == x) return true;
			if(sum < x) return false;
		}		
		return true;
	}

	public static void main (String[] args) throws java.lang.Exception
	{
		long time = System.currentTimeMillis();

		Vector triangle = new Vector(); triangle.add(1); 
		String[] in = {"Found @ http://archiver.joshho.com/display.php?full=1&q=http://projecteuler.net/project/words.txt"};  

		int count = 0;
		for(String x : in){
			int sum = 0;
			for(int i=0; i