update 12 problem solution

Author: 6boris

src/0013.Roman-to-Integer/README.md

@@ -78,29 +78,23 @@ Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
 
 那么我们可以利用 map 来完成罗马数字的 7 个数字符号：I、V、X、L、C、D、M 和整数的映射关系，然后根据上面的解释来模拟完成即可。
 
-```java
-class Solution {
-    public int romanToInt(String s) {
-        Map<Character, Integer> map = new HashMap<>();
-        map.put('I', 1);
-        map.put('V', 5);
-        map.put('X', 10);
-        map.put('L', 50);
-        map.put('C', 100);
-        map.put('D', 500);
-        map.put('M', 1000);
-        int len = s.length();
-        int sum = map.get(s.charAt(len - 1));
-        for (int i = len - 2; i >= 0; --i) {
-            if (map.get(s.charAt(i)) < map.get(s.charAt(i + 1))) {
-                sum -= map.get(s.charAt(i));
-            } else {
-                sum += map.get(s.charAt(i));
-            }
-        }
-        return sum;
-    }
+```go
+func romanToInt(s string) int {
+	m := map[string]int{"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}
+	sum := m[string(s[len(s)-1])]
+	// 从后向前遍历
+	// 每次和前面一位数比较
+	for i := len(s) - 2; i >= 0; i-- {
+		if m[string(s[i])] < m[string(s[i+1])] {
+			sum -= m[string(s[i])]
+		} else {
+			sum += m[string(s[i])]
+		}
+	}
+
+	return sum
 }
+
 ```
 
 

src/0013.Roman-to-Integer/Solution.go

@@ -1,27 +1,34 @@
 package Solution
 
 func romanToInt(s string) int {
-	//	初始化一个罗马字符的Map
-	romanMap := map[string]int{}
-	romanMap["I"] = 1
-	romanMap["V"] = 5
-	romanMap["X"] = 10
-	romanMap["L"] = 50
-	romanMap["C"] = 100
-	romanMap["D"] = 500
-	romanMap["M"] = 1000
-
-	MapIndex := string(s[len(s)-1])
-	sum := romanMap[MapIndex]
+	m := map[string]int{"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}
+	sum := m[string(s[len(s)-1])]
+	// 从后向前遍历
+	// 每次和前面一位数比较
 	for i := len(s) - 2; i >= 0; i-- {
-		//	左小右大
-		if romanMap[string(s[i])] < romanMap[string(s[i+1])] {
-			sum -= romanMap[string(s[i])]
-			//	左大右小
+		if m[string(s[i])] < m[string(s[i+1])] {
+			sum -= m[string(s[i])]
 		} else {
-			sum += romanMap[string(s[i])]
+			sum += m[string(s[i])]
 		}
 	}
 
 	return sum
 }
+
+func romanToInt2(s string) int {
+	m := map[string]int{"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}
+	ans := 0
+	// 从前向后遍历
+	// 每次默认相加再检查和前面一位数的大小
+	// 前面 > 后面  ans = s[i-1] + s[i]
+	// 前面 < 后面  ans = - (2 * s[i-1]) + s[i] (因为默认加了一次所以需要减2次)
+	for i, _ := range s {
+		ans += m[string(s[i])]
+		if i > 0 && m[string(s[i])] > m[string(s[i-1])] {
+			ans -= 2 * m[string(s[i-1])]
+		}
+	}
+	return ans
+
+}

src/0013.Roman-to-Integer/Solution_test.go

@@ -1,46 +1,59 @@
 package Solution
 
-import "testing"
+import (
+	"reflect"
+	"strconv"
+	"testing"
+)
 
 func TestSolution(t *testing.T) {
-	t.Run("Test-1", func(t *testing.T) {
-		got := romanToInt("III")
-		want := 3
-		if got != want {
-			t.Error("GOT:", got, "WANT:", want)
-		}
-	})
+	//	测试用例
+	cases := []struct {
+		name   string
+		inputs string
+		expect int
+	}{
+		{"TestCase", "III", 3},
+		{"TestCase", "IV", 4},
+		{"TestCase", "IX", 9},
+		{"TestCase", "LVIII", 58},
+		{"TestCase", "MCMXCIV", 1994},
+	}
 
-	t.Run("Test-2", func(t *testing.T) {
-		got := romanToInt("IV")
-		want := 4
-		if got != want {
-			t.Error("GOT:", got, "WANT:", want)
-		}
-	})
-
-	t.Run("Test-3", func(t *testing.T) {
-		got := romanToInt("IX")
-		want := 9
-		if got != want {
-			t.Error("GOT:", got, "WANT:", want)
-		}
-	})
-
-	t.Run("Test-4", func(t *testing.T) {
-		got := romanToInt("LVIII")
-		want := 58
-		if got != want {
-			t.Error("GOT:", got, "WANT:", want)
-		}
-	})
+	//	开始测试
+	for i, c := range cases {
+		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
+			got := romanToInt(c.inputs)
+			if !reflect.DeepEqual(got, c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
+					c.expect, got, c.inputs)
+			}
+		})
+	}
+}
 
-	t.Run("Test-5", func(t *testing.T) {
-		got := romanToInt("MCMXCIV")
-		want := 1994
-		if got != want {
-			t.Error("GOT:", got, "WANT:", want)
-		}
-	})
+func TestSolution2(t *testing.T) {
+	//	测试用例
+	cases := []struct {
+		name   string
+		inputs string
+		expect int
+	}{
+		{"TestCase", "III", 3},
+		{"TestCase", "IV", 4},
+		{"TestCase", "IX", 9},
+		{"TestCase", "LVIII", 58},
+		{"TestCase", "MCMXCIV", 1994},
+	}
 
+	//	开始测试
+	for i, c := range cases {
+		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
+			got := romanToInt2(c.inputs)
+			if !reflect.DeepEqual(got, c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
+					c.expect, got, c.inputs)
+			}
+		})
+	}
 }