Roman to Integer Leetcode

Given a Roman numeral, convert it to an integer.

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

The title means converting a given Roman number to an integer.

What are Roman numerals:

I, II, III, IV, V, VI, VII, VIII, IX, X .

The above Roman numerals are expressed as 1 2 3 4 5 6 7 8 9 10

in Roman numerals, the numbers corresponding to each character are the same as above, and the highest-level characters are m followed by the smallest of D as I
Rules:from right to left, encountered lower than the previous character level or the same as the character corresponding to the numeric value of the representation and accumulation as VII as 1+ 1+ 5 =7 A numeric value that corresponds to a higher than the previous character minus the character, such as IV as 5-1=4, is encountered The code is as follows:

<span style= "FONT-SIZE:18PX;" >class Solution {public:/* symbolvalue I1 V5 X10 L50 C100 D500 m1,000 *//need to be aware of Roman numerals    There is subtraction, which iterates from the forward int romantoint (string s) {int result=0;     To record which unit was last seen, use a number to record which unit occurred last, 1 2 3 4 5 6 7 for the first value of the I V X L C D M int last_show=0;//is 0 when the last occurrence value is less than or equal to the current value with addition, otherwise there is subtraction int cur_show;                Current value for (Int. i=s.length () -1;i>=0;i--) {switch (S[i]) {case ' I ':                Cur_show=1;                if (cur_show>=last_show) result+=1;                else result-=1;                            Break                Case ' V ': cur_show=2;                if (cur_show>=last_show) result+=5;                else result-=5;                            Break               Case ' X ': cur_show=3;               if (cur_show>=last_show) result+=10; else result-=10;                             Break                Case ' L ': cur_show=4;                if (cur_show>=last_show) result+=50;                else result-=50;                            Break                Case ' C ': cur_show=5;                if (cur_show>=last_show) result+=100;                else result-=100;                            Break                Case ' D ': cur_show=6;                if (cur_show>=last_show) result+=500;                else result-=500;            Break                Case ' M ': cur_show=7;                if (cur_show>=last_show) result+=1000;                else result-=1000;            Break                            Default:break;    } last_show=cur_show;      }  return result; }};</span>

Roman to Integer Leetcode