Roman to Integer

06/23/2016 String Math

Question

Given a roman numeral, convert it to an integer.

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

Solution

Result: Accepted Time: 24ms

Here should be some explanations.

int romanToInt(char* str) {
    int table[256] = {0};
    const char keys[]="IVXLCDM";
    const int values[]={1,5,10,50,100,500,1000};
    for(int i = 0; i < sizeof(keys); i++)
        table[keys[i]] = table[keys[i] | 32] = values[i];
    int ans = 0, last = 0, now = 0;
    while(*str)
    {
        now = table[*(str++)];
        ans += now;
        if(last < now)
            ans -= (last << 1);
        last = now;
    }
    return ans;
}

Complexity Analytics

  • Time Complexity:
  • Space Complexity: