Add Solution2.go for 0013.Roman to Integer

Author: electricbubble

solution/0013.Roman to Integer/Solution2.go

@@ -0,0 +1,14 @@
+func romanToInt(s string) int {
+	symbols := map[string]int{"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}
+	ret := 0
+	l := len(s)
+	for i := 0; i < l-1; i++ {
+		if symbols[s[i:i+1]] < symbols[s[i+1:i+2]] {
+			ret -= symbols[s[i:i+1]]
+		} else {
+			ret += symbols[s[i:i+1]]
+		}
+	}
+	ret += symbols[s[l-1:]]
+	return ret
+}