LeetCode-13. Roman to Integer

Topic:

Given a Roman numeral, convert it to an integer.

Input is guaranteed to being within the range from 1 to 3999.

Problem Solving Ideas:

The previous article has introduced the composition and calculation of Roman numerals, so it is easier to convert Roman numerals into integers.

The way I thought before was to judge the character from left to right and to subtract or other 1,10,100, but it was a lot simpler to see a right-to-left calculation.

When calculating from right to left, it is only necessary to determine whether the current number is not less than 5 or 50,500 when encountering 1,10,100.

C # code:

 Public classSolution { Public intRomantoint (strings) {intresult =0;  for(inti = s.length-1; I >=0; i--)        {            Switch(S[i]) { Case 'I': Result+ = (Result >=5) ? -1:1;  Break;  Case 'V': Result+=5;  Break;  Case 'X': Result+ = (Result >= -) ? -Ten:Ten;  Break;  Case 'L': Result+= -;  Break;  Case 'C': Result+ = (Result >= -) ? - -: -;  Break;  Case 'D': Result+= -;  Break;  Case 'M': Result+= +;  Break; default:                    return 0; }        }        returnresult; }}

View Code

LeetCode-13. Roman to Integer