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82 lines (76 loc) · 2.79 KB
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/**
* Created by D on 3/4/2015.
*/
/*
Create a function taking a positive integer as its parameter and returning a string containing the Roman Numeral
representation of that integer.
Modern Roman numerals are written by expressing each digit separately starting with the left most digit and skipping
any digit with a value of zero. In Roman numerals 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC. 2008 is
written as 2000=MM, 8=VIII; or MMVIII. 1666 uses each Roman symbol in descending order: MDCLXVI.
Example:
solution(1000); // should return 'M'
Help:
Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1,000
Remember that there can't be more than 3 identical symbols in a row.
*/
function solution(number){
var romanNums = ['I', 'V', 'X', 'L', 'C', 'D', 'M'];
var numberStr = number + '';
var romanStr = '';
var digitToEval = numberStr.length; //which decimal place the loop is currently changing to roman numeral
var modifier; //this modifier will tell us how which roman numerals to use in romanNums array
for (var i = 0, len = digitToEval; i < len; i++) {
switch (digitToEval){//sets modifier which determines which roman numerals to use
case 4:
modifier = 6;
break;
case 3:
modifier = 4;
break;
case 2:
modifier = 2;
break;
case 1:
modifier = 0;
break;
}
switch(+numberStr.substr(i, 1)){ //sets digit to appropriate roman rep. and adds to roman numeral str.
case 9:
romanStr += romanNums[modifier] + romanNums[modifier + 2];
break;
case 8:
romanStr += romanNums[modifier + 1] + romanNums[modifier] + romanNums[modifier] + romanNums[modifier];
break;
case 7:
romanStr += romanNums[modifier + 1] + romanNums[modifier] + romanNums[modifier];
break;
case 6:
romanStr += romanNums[modifier + 1] + romanNums[modifier];
break;
case 5:
romanStr += romanNums[modifier + 1];
break;
case 4:
romanStr += romanNums[modifier] + romanNums[modifier + 1];
break;
case 3:
romanStr += romanNums[modifier] + romanNums[modifier] + romanNums[modifier];
break;
case 2:
romanStr += romanNums[modifier] + romanNums[modifier];
break;
case 1:
romanStr += romanNums[modifier];
break;
}
digitToEval = digitToEval - 1;
}
return romanStr;
}