标签：style blog color io ar for div sp log
Given a roman numeral, convert it to an integer.
Input is guaranteed to be within the range from 1 to 3999.
思路：从后往前遍历，如果某个数比其后一个数小，则减去该数；否则，加上该数。因为只存在Ⅳ(4)、XL(40)、CD(400)等一类的逆序情况，而这些数的共同点是前一个数的重复次数均为1。
1 class Solution { 2 public: 3 int romanToInt( string s ) { 4 if( s.empty() ) { return 0; } 5 unordered_map<char,int> romanMap; 6 romanMap[‘I‘] = 1; 7 romanMap[‘V‘] = 5; 8 romanMap[‘X‘] = 10; 9 romanMap[‘L‘] = 50; 10 romanMap[‘C‘] = 100; 11 romanMap[‘D‘] = 500; 12 romanMap[‘M‘] = 1000; 13 int ret = romanMap[s.back()]; 14 for( int i = (int)s.size()-2; i >= 0 ; --i ) { 15 if( romanMap[s[i]] < romanMap[s[i+1]] ) { 16 ret -= romanMap[s[i]]; 17 } else { 18 ret += romanMap[s[i]]; 19 } 20 } 21 return ret; 22 } 23 };
标签：style blog color io ar for div sp log
原文地址：http://www.cnblogs.com/moderate-fish/p/3960394.html
