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1 | 1 | var romanToInt = function(s) { |
2 | | -let ans = 0; |
| 2 | +let ans = 0; // ans stores value of roman no. |
| 3 | +// objects are used to refracter the code |
| 4 | +// reducing multiple ifs to single if |
3 | 5 | let [obj1,obj2] = [{"I":2,"X":20},{"I":2,"X":20,"C":200}] |
| 6 | +// loop the roman no. string |
4 | 7 | for(let i = 0 ; i < s.length;i++){ |
| 8 | + // if I add 1 to ans |
5 | 9 | if( s[i] == "I" ){ans += 1} |
| 10 | + // if V add 5 to ans |
6 | 11 | if( s[i] == "V" ){ |
7 | 12 | ans += 5 |
| 13 | + // if we have IV that means 4 but |
| 14 | + // we have already add 1 in previous iteration |
| 15 | + // we need to subtract 2 to make it 4 |
8 | 16 | if( s[i-1] == "I" ) {ans -= 2} |
9 | 17 | } |
| 18 | + // if X add 10 to ans |
10 | 19 | if( s[i] == "X" ){ |
11 | 20 | ans += 10 |
| 21 | + // if we have IX that means 9 but |
| 22 | + // we have already add 1 in previous iteration |
| 23 | + // we need to subtract 2 to make it 9 |
12 | 24 | if( s[i-1] == "I" ) {ans -= 2} |
13 | 25 | } |
| 26 | + // if L add 50 to ans |
14 | 27 | if( s[i] == "L" ){ |
15 | 28 | ans += 50 |
| 29 | + // we check the for any IL or XL combination |
| 30 | + // subtract the value accordingly |
16 | 31 | if(obj1[s[i-1]]){ans -= obj1[s[i-1]]} |
17 | 32 | } |
| 33 | + // if C add 100 to ans |
18 | 34 | if( s[i] == "C" ){ |
19 | 35 | ans += 100 |
| 36 | + // we check the for any IC or XC combination |
| 37 | + // subtract the value accordingly |
20 | 38 | if(obj1[s[i-1]]){ans -= obj1[s[i-1]]} |
21 | 39 | } |
| 40 | + // if D add 500 to ans |
22 | 41 | if( s[i] == "D" ){ |
23 | 42 | ans += 500 |
| 43 | + // we check the for any ID or XD or CD combination |
| 44 | + // subtract the value accordingly |
24 | 45 | if(obj2[s[i-1]]){ans -= obj2[s[i-1]]} |
25 | 46 | } |
| 47 | + // if M add 1000 to ans |
26 | 48 | if( s[i] == "M"){ |
27 | 49 | ans += 1000 |
| 50 | + // we check the for any IM or XM or CM combination |
| 51 | + // subtract the value accordingly |
28 | 52 | if(obj2[s[i-1]]){ans -= obj2[s[i-1]]} |
29 | 53 | } |
30 | 54 | } |
31 | 55 | return ans |
32 | | -}; |
| 56 | +}; |
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