mathball/lib/smith/index.js

A JavaScript library for Competitive Programming

'use strict';

/* Smith Number
 * Function: isSmith()
 */

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

var primes = new Array();
var MAX = 10000;

function sieveSundaram() {
	var marked = new Array(Math.floor(MAX / 2) + 100);
	for (var i = 0; i < Math.floor(MAX / 2) + 100; i++) {
		marked[i] = false;
	}

	for (var _i = 1; _i <= Math.floor((Math.sqrt(MAX) - 1) / 2); _i++) {
		for (var j = _i * (_i + 1) << 1; j <= Math.floor(MAX / 2); j = j + 2 * _i + 1) {
			marked[j] = true;
		}
	}
	primes.push(2);
	for (var _i2 = 1; _i2 <= Math.floor(MAX / 2); _i2++) {
		if (marked[_i2] === false) {
			primes.push(2 * _i2 + 1);
		}
	}
}

function smith(num) {
	var originalNo = num;
	var pDigitSum = 0;
	for (var i = 0; primes[i] <= Math.floor(num / 2); i++) {
		while (num % primes[i] === 0) {
			var p = primes[i];
			num = Math.floor(num / p);
			while (p > 0) {
				pDigitSum = pDigitSum + p % 10;
				p = Math.floor(p / 10);
			}
		}
	}

	if (num !== 1 && num !== originalNo) {
		while (num > 0) {
			pDigitSum = pDigitSum + num % 10;
			num = Math.floor(num / 10);
		}
	}

	var sumDigits = 0;
	while (originalNo > 0) {
		sumDigits = sumDigits + originalNo % 10;
		originalNo = Math.floor(originalNo / 10);
	}
	return pDigitSum === sumDigits;
}

exports.check = function (num) {
	validate(num, 'isSmith');
	sieveSundaram();
	return smith(num);
};