diff --git a/leetcode/777777/5629. Reformat Phone Number.go b/leetcode/777777/5629. Reformat Phone Number.go
new file mode 100644
index 000000000..70795214f
--- /dev/null
+++ b/leetcode/777777/5629. Reformat Phone Number.go	
@@ -0,0 +1,51 @@
+package leetcode
+
+func reformatNumber(number string) string {
+	str, count := "", 0
+	for i := 0; i < len(number); i++ {
+		if number[i] != '-' && number[i] != ' ' {
+			str += string(number[i])
+			// str = append(str, number[i])
+		}
+	}
+	if len(str) == 4 {
+		str = str[:2] + "-" + str[2:]
+		return str
+	}
+	if len(str) > 3 {
+		if (len(str)-4)%3 == 0 {
+			for i := len(str) - 5; i >= 0; i-- {
+				count++
+				if count%3 == 0 && i != 0 {
+					str = str[:i] + "-" + str[i:]
+				}
+			}
+			str = str[:len(str)-2] + "-" + str[len(str)-2:]
+			str = str[:len(str)-5] + "-" + str[len(str)-5:]
+			return str
+		}
+		if (len(str)-2)%3 == 0 {
+			for i := len(str) - 3; i >= 0; i-- {
+				count++
+				if count%3 == 0 && i != 0 {
+					str = str[:i] + "-" + str[i:]
+				}
+			}
+			str = str[:len(str)-2] + "-" + str[len(str)-2:]
+			return str
+		}
+		length := len(str)
+		count = 0
+		for j := 0; j < len(str); j++ {
+			count++
+			if count%3 == 0 && count != length {
+				// head :=
+				// tail :=
+				str = str[:j+1] + "-" + str[j+1:]
+				j++
+			}
+		}
+
+	}
+	return str
+}
diff --git a/leetcode/777777/5629. Reformat Phone Number_test.go b/leetcode/777777/5629. Reformat Phone Number_test.go
new file mode 100644
index 000000000..8aba62c99
--- /dev/null
+++ b/leetcode/777777/5629. Reformat Phone Number_test.go	
@@ -0,0 +1,67 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question1690 struct {
+	para1690
+	ans1690
+}
+
+// para 是参数
+// one 代表第一个参数
+type para1690 struct {
+	number string
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans1690 struct {
+	one string
+}
+
+func Test_Problem1690(t *testing.T) {
+
+	qs := []question1690{
+
+		{
+			para1690{"1-23-45 6"},
+			ans1690{"123-456"},
+		},
+
+		{
+			para1690{"123 4-567"},
+			ans1690{"123-45-67"},
+		},
+
+		{
+			para1690{"123 4-5678"},
+			ans1690{"123-456-78"},
+		},
+
+		{
+			para1690{"12"},
+			ans1690{"12"},
+		},
+
+		{
+			para1690{"--17-5 229 35-39475 "},
+			ans1690{"175-229-353-94-75"},
+		},
+
+		{
+			para1690{"9964-"},
+			ans1690{"99-64"},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 1690------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans1690, q.para1690
+		fmt.Printf("【input】:%v       【output】:%v\n", p, reformatNumber(p.number))
+	}
+	fmt.Printf("\n\n\n")
+}