Add: Greatest Common Divisor of Strings

problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings.go

@@ -1,36 +1,17 @@
 package problem1071
 
-import "strings"
-
-func gcdOfStrings(s1, s2 string) string {
-	l1, l2 := len(s1), len(s2)
-	d := gcd(max(l1, l2), min(l1, l2))
-	p := s2[:d]
-	if s1 == strings.Repeat(p, l1/d) &&
-		s2 == strings.Repeat(p, l2/d) {
-		return p
+func gcdOfStrings(str1 string, str2 string) string {
+	if str1+str2 != str2+str1 {
+		return ""
 	}
-	return ""
+	return str1[:gcd(len(str1), len(str2))]
 }
 
-// a >= b
+// 最大公约数（Greatest Common Divisor）缩写为GCD
+// 辗转相除法
 func gcd(a, b int) int {
 	if b == 0 {
 		return a
 	}
 	return gcd(b, a%b)
 }
-
-func min(a, b int) int {
-	if a < b {
-		return a
-	}
-	return b
-}
-
-func max(a, b int) int {
-	if a > b {
-		return a
-	}
-	return b
-}

problems/greatest-common-divisor-of-strings/greatest_common_divisor_of_strings_test.go

@@ -0,0 +1,35 @@
+package problem1071
+
+import "testing"
+
+type testType struct {
+	str1 string
+	str2 string
+	want string
+}
+
+func TestGcdOfStrings(t *testing.T) {
+	tests := [...]testType{
+		{
+			str1: "ABCABC",
+			str2: "ABC",
+			want: "ABC",
+		},
+		{
+			str1: "ABABAB",
+			str2: "ABAB",
+			want: "AB",
+		},
+		{
+			str1: "LEET",
+			str2: "CODE",
+			want: "",
+		},
+	}
+	for _, tt := range tests {
+		got := gcdOfStrings(tt.str1, tt.str2)
+		if got != tt.want {
+			t.Fatalf("in: %v, got: %v, want: %v", tt.str1, got, tt.want)
+		}
+	}
+}