Add Soulution.go for 0013.Roman to Integer

Author: Yeqi Tao

solution/0013.Roman to Integer/Solution.go

@@ -0,0 +1,41 @@
+// 字符          数值
+// I             1
+// V             5
+// X             10
+// L             50
+// C             100
+// D             500
+// M             1000
+var table = make(map[string]int)
+
+func init() {
+	table["I"] = 1
+	table["IV"] = 4
+	table["V"] = 5
+	table["IX"] = 9
+	table["X"] = 10
+	table["XL"] = 40
+	table["L"] = 50
+	table["XC"] = 90
+	table["C"] = 100
+	table["CD"] = 400
+	table["D"] = 500
+	table["CM"] = 900
+	table["M"] = 1000
+}
+
+func romanToInt(s string) int {
+	var result int
+	lenS := len(s)
+	for i:=0; i<lenS; i++ {
+		if i < lenS - 1 {
+			if v, exist := table[s[i:i+2]]; exist {
+				result += v
+				i++
+				continue
+			}
+		}
+        result += table[string(s[i])]
+	}
+	return result
+}