11import java .util .*;
2+
23public class RomanToInteger {
3-
4- /*
5- This function convert Roman number into Integer
6- @param A is Roman number string
7- */
8- public static int romanToInt (String A ) {
9- Map <Character ,Integer >map =new HashMap <>();
10- map .put ('I' ,1 );
11- map .put ('V' ,5 );
12- map .put ('X' ,10 );
13- map .put ('L' ,50 );
14- map .put ('C' ,100 );
15- map .put ('D' ,500 );
16- map .put ('M' ,1000 );
17-
18- char c =A .charAt (A .length ()-1 );
19- char prev =' ' ;
20-
21- int sum =0 ;
22-
23- int newPrev =0 ,currentNum =0 ;
24- for (int i =A .length () -1 ;i >=0 ;i --)
25- {
26- c =A .charAt (i );
27-
28-
29- if (prev !=' ' ) {
30- //checking current Number greater then previous or not
31- newPrev =map .get (prev ) >newPrev ?map .get (prev ) :newPrev ;
32- }
33-
34-
35- currentNum =map .get (c );
36-
37- if (currentNum >=newPrev )//if current number greater then prev max previous then add
38- {
39- sum +=currentNum ;
40- }
41- else {
42-
43- sum -=currentNum ;// subtract upcoming number until upcoming number not greater then prev max
44- }
45-
46- prev =c ;
47- }
48-
49- return sum ;
50- }
514
5+ private static Map <Character ,Integer >map =new HashMap <>() {{
6+ put ('I' ,1 );
7+ put ('V' ,5 );
8+ put ('X' ,10 );
9+ put ('L' ,50 );
10+ put ('C' ,100 );
11+ put ('D' ,500 );
12+ put ('M' ,1000 );
13+ }};
14+
15+ /**
16+ * This function convert Roman number into Integer
17+ *
18+ * @param A Roman number string
19+ * @return integer
20+ */
21+ public static int romanToInt (String A ) {
22+
23+ char prev =' ' ;
24+
25+ int sum =0 ;
26+
27+ int newPrev =0 ;
28+ for (int i =A .length () -1 ;i >=0 ;i --) {
29+ char c =A .charAt (i );
5230
53- public static void main (String []args ) {
54-
55-
56- int sum =romanToInt ("MDCCCIV" ) ;
57- System .out .println (sum );
58- }
31+ if (prev !=' ' ) {
32+ // checking current Number greater then previous or not
33+ newPrev =map .get (prev ) >newPrev ?map .get (prev ) :newPrev ;
34+ }
5935
60- }
36+ int currentNum =map .get (c );
37+
38+ // if current number greater then prev max previous then add
39+ if (currentNum >=newPrev ) {
40+ sum +=currentNum ;
41+ }else {
42+ // subtract upcoming number until upcoming number not greater then prev max
43+ sum -=currentNum ;
44+ }
45+
46+ prev =c ;
47+ }
48+
49+ return sum ;
50+ }
51+
52+ public static void main (String []args ) {
53+ int sum =romanToInt ("MDCCCIV" );
54+ System .out .println (sum );
55+ }
56+ }