Problem 42(Coded triangle numbers)

Problem 42(Coded triangle numbers)

The \( n^{th} \) term of the sequence of triangle numbers is given by, \( t_{n} = \frac{1}{2} n(n+1) \) so the first ten triangle numbers are:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ...

By converting 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 \(19 + 11 + 25 = 55 = t_{10}\). If the word value is a triangle number then we shall call the word a triangle word.

Using words.txt (right click and 'Save Link/Target As...'), a 16K text file containing nearly two-thousand common English words, how many are triangle words?

 

In Python:

import time

startTime = time.time()
f = open("./PE42_words.txt", 'r')
dataSet = [strWord[1: -1] for strWord in f.read().split(",")]
f.close()

count = 0
triNumList = [int(0.5 * n * (n + 1)) for n in range(1, 100)]

for data in dataSet:
    lenData = len(data)
    sumAscii = 0
    for i in range(lenData):
        sumAscii += ord(data[i]) - 64
    if sumAscii in triNumList:
        count += 1
print(count)
print(time.time() - startTime, "seconds")

Run time: 0.0182950496673584 seconds

 

 

In Java:

package project_euler41_50;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;


public class Euler42 {
	public static void main(String[] args) throws IOException {
		long startTime = System.currentTimeMillis();
		int count = 0;
		String data[];
		ArrayList<Integer> triNumList = new ArrayList<Integer>();
		ArrayList<String> dataList = new ArrayList<String>();
		BufferedReader br = new BufferedReader (new FileReader("./Euler42_words.txt"));
		while(true) {
			String line = br.readLine();
			if (line == null) break;
			data = line.split(",");
			for (int i = 0; i < data.length; i++) {
				dataList.add(data[i].substring(1, data[i].length() - 1));
			}
		}
		br.close();
		for (int i = 1; i < 100; i++) {
			triNumList.add((int)(0.5 * i * (i + 1)));
		}
		for (String word : dataList) {
			int lenWord = word.length();
			int sumAscii = 0;
			for (int i = 0; i < lenWord; i++) {
				sumAscii += word.charAt(i) - 64;
			}
			if (triNumList.contains(sumAscii)) {
				count ++;
			}
		}
		System.out.println(count);
		long endTime = System.currentTimeMillis();
		System.out.println((double)(endTime - startTime)/(double)1000 + "seconds");
	}
}

Run time: 0.016seconds

 

Solution: 162