13. 罗马数字转整数 LeetCode

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class Solution {
    func romanToInt(_ s: String) -> Int {
        let dic = ["I"       :      1,
                   "V"       :      5,
                   "X"       :      10,
                   "L"       :      50,
                   "C"       :      100,
                   "D"       :      500,
                   "M"       :      1000]
        var arr:[String] = [];
        for c in s{
            arr.append(String(c));
        }
        
        var result = 0;
        for i in 0..<arr.count{
            if i+1 < arr.count{
                if arr[i] == "I",(arr[i+1] == "V" || arr[i+1] == "X"){
                    result = result - dic[arr[i]]! ;
                }else if arr[i] == "X",(arr[i+1] == "L" || arr[i+1] == "C"){
                    result = result - dic[arr[i]]! ;
                }else if arr[i] == "C",(arr[i+1] == "D" || arr[i+1] == "M"){
                    result = result - dic[arr[i]]! ;
                }else{
                    result = result + dic[arr[i]]!
                }
            }else{
                result = result + dic[arr[i]]!
            }
            
        }
        if result > 3999 || result < 1{
            return 0
        }
        return result
    }
}