https://www.codeeval.com/open_challenges/139

chalenge139.js

var fs = require("fs");
var monMap = {
	'Jan': 1,
	'Feb': 2,
	'Mar': 3,
	'Apr': 4,
	'May': 5,
	'Jun': 6,
	'Jul': 7,
	'Aug': 8,
	'Sep': 9,
	'Oct': 10,
	'Nov': 11,
	'Dec': 12
};

function toNum(dateStr) {
	var p = dateStr.split(' ');

	return parseInt(p[1], 10) + monMap[p[0]] / 100;
}

function Range(rangeStr) {
	var rangeArr = rangeStr.split('-');

	this.start = toNum(rangeArr[0]);
	this.end = toNum(rangeArr[1]);
}

Range.create = function (rangeStr) {
	return new Range(rangeStr);
}

Range.prototype.months = function () {
	var ydiff = Math.floor(this.end) - Math.floor(this.start);
	var mstart = Math.floor((this.start - Math.floor(this.start)) * 100);
	var mend = Math.floor((this.end - Math.floor(this.end)) * 100);

	return mend - mstart + 1 + ydiff * 12;
};

Range.prototype.compare = function (range) {
	if (this.start < range.start) {
		return -1;
	} else if (this.start > range.start) {
		return 1;
	}

	return 0;
};

Range.prototype.merge = function (range) {
	if (range.end >= this.start && range.start <= this.end) {
		this.start = Math.min(this.start, range.start);
		this.end = Math.max(this.end, range.end);
		return true;
	}

	return false;
};

function lineToRanges(line) {
	return line.split('; ')
		.map(Range.create);
}

function rangesToMonths(ranges) {
	return ranges
		.sort(function (r1, r2) {
			return r1.compare(r2);
		})
		.reduce(function (acc, range) {
			for (var i = 0; i < acc.length; i++) {
				if (acc[i].merge(range)) {
					range = undefined;
					break;
				}
			}
			if (range) {
				acc.push(range);
			}

			return acc;
		}, [])
		.reduce(function (months, range) {
			return months + range.months();
		}, 0)
		;
}

function monthsToYears(months) {
	return Math.floor(months / 12);
}

fs
	.readFileSync(process.argv[2])
	.toString()
	.split('\n')
	.filter(function (line) {
		return line.trim() !== '';
	})
	.map(lineToRanges)
	.map(rangesToMonths)
	.map(monthsToYears)
	.forEach(function (years) {
		console.log(years);
	})
	;