mathball/lib/triangular/index.js

A JavaScript library for Competitive Programming

'use strict';

/*Triangular Number
*Function: M.triangular()
*/

var validate = require('../validation/positive-integer');

var triangular = function triangular(n) {
	var sum = 0;
	for (var i = 0; i < n; i++) {
		sum += n - i;
	}
	return sum;
};

exports.find = function (n) {
	validate(n, 'triangular');
	return triangular(n);
};