leetcode - intToRoman.js

intToRoman.js

/*
author Oleg Kornilov
[email protected], https://github.com/OlegKorn
*/

var intToRoman = function(num) {

    var equivalents = {
		1: "I", 
		4: "IV", 
		5: "V", 
		9: "IX", 
		10: "X",
		40: "XL",
		50: "L",
		90: "XC",
		100: "C",
		400: "CD",
		500: "D",
		900: "CM",
		1000: "M"
	}
    
    function isThereEquivalent(equivalentsArr, value) {
    	try {
    		var equivalent = Object.entries(equivalentsArr).find(([key]) => key === value.toString())[1] 

    		return equivalent
    	}
    	
    	catch (e) {
    		if (e instanceof TypeError) {
    		    return false 
    		}
    	}  
    }


    var decimals = []
    var convertedToRoman = ""
	var nStr = num.toString()

	for (var i = nStr.length; i > 0; i--) {    	
		var decimalPosition = nStr.slice(-i)

		if (decimalPosition[0] === "0") {
			continue
		}

		var toSubstract = decimalPosition.substring(1, decimalPosition.length)
		var clearDecimalPosition = Number(decimalPosition) - Number(toSubstract)
		decimals.push(clearDecimalPosition) 
	}

	for (var i = 0; i < decimals.length; i++) {
		// if decimals[i] has its letter equivalent
		if (isThereEquivalent(equivalents, decimals[i])) {
    	    convertedToRoman += isThereEquivalent(equivalents, decimals[i]).toString()
    	    // console.log(decimals[i], isThereEquivalent(equivalents, decimals[i]), convertedToRoman)
    	    continue
		}

		// if decimals[i] is >= 1000
		if (decimals[i].toString().length > 3) {
	        // now have to decompose this.decimalPositions[i] into its closestEquivalent and remainders
	        var closestEquivalent = Number(Object.keys(equivalents)[Object.keys(equivalents).length - 1])
	        var howManyEquivalentsInThis = decimals[i] / closestEquivalent 
           	var closestEquivalentLetterValue = isThereEquivalent(equivalents, closestEquivalent)
           	var equivalent = closestEquivalentLetterValue.repeat(howManyEquivalentsInThis)

           	convertedToRoman += equivalent
	    }

	    for (var j = 0; j < Object.keys(equivalents).length; j++) {
	    	// find closest eqiuvalents of decimals[i] so that it's between them
	    	// e.g. 500 700 900 
	    	if ((decimals[i] < Object.keys(equivalents)[j+1]) && (decimals[i] > Object.keys(equivalents)[j])) {
	            // now have to decompose this.decimalPositions[i] into its closestEquivalent and remainders
		        var closestEquivalent = Number(Object.keys(equivalents)[j]) // 500
		        var closestEquivalentLetter = isThereEquivalent(equivalents, closestEquivalent) // D
		        convertedToRoman += closestEquivalentLetter

		        // 200
	    	    var remained = decimals[i] - closestEquivalent // 200 
	    	    var remainedEquivalent = remained / Number(remained.toString().charAt(0)) // 100
	    	    var howManyEquivalentsInRemained = remained / Number(remainedEquivalent) // 2

	    	    var counter = howManyEquivalentsInRemained

	    	    while (counter !== 0) {
	    	    	var remainedLetters = isThereEquivalent(equivalents, remainedEquivalent).repeat(1)
	        	    convertedToRoman += remainedLetters
	        	    
	        	    counter -= 1
	    	    }
	        }
	    }
	}

	return convertedToRoman
}