Leetcode--Roman to Integer

Title Description:
Given a Roman numeral, convert it to an integer.


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


is to convert Roman numerals into integers.


1. First understand the integer corresponding to the Roman numerals:
CharacterIVXLCDM
Digital1510501005001000


2. Conversion rules
In Roman string S, for S[i] and s[i+1], if the s[i+1] number is small, then the integer is s[i]+s[i+1], otherwise:
If S[I+1] is larger than s[i], then s[i] and s[i+1] represent s[i+1]-s[i].


Ideas:
Traverse Roman string s, each mapped to a character, total initialized to s[0],i∈[0,n), compare s[i] and s[i+1], if the latter is directly cumulative s[i+1], otherwise subtract s[i] twice times and add the current number s[i+1].




Implementation code:

public class Solution {public    int romantoint (string s)     {       if (string. IsNullOrEmpty (s))       {    return 0;    }        var len = s.length;    var result = Convert (S[0]);    if (Len < 2) {    return result;    }    for (var i = 1;i < Len; i++) {    var pre = Convert (S[i-1]);    var current = Convert (S[i]);        if (current <= pre) {    result + = current;    } else{    result = result-2 * pre + current;    }    }        return result;    } private int Convert (char c) {switch (c) {case ' I ':  return 1;case ' V ': Return 5;case ' X ':  return;  Case ' L ':  return;  Case ' C ':  return;  Case ' D ':  return;  Case ' M ':  return;  Default:throw new ArgumentException ();}}}

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Leetcode--Roman to Integer