diff --git a/src/0241.Different-Ways-to-Add-Parentheses/Solution.go b/src/0241.Different-Ways-to-Add-Parentheses/Solution.go
index 6a10aa77e..cfc60fd35 100644
--- a/src/0241.Different-Ways-to-Add-Parentheses/Solution.go
+++ b/src/0241.Different-Ways-to-Add-Parentheses/Solution.go
@@ -1,5 +1,55 @@
 package Solution
 
+import "strconv"
+
 func diffWaysToCompute(input string) []int {
-	return []int{}
+	return ways(input, map[string][]int{})
+}
+
+func calculate(a, b int, operate rune) int {
+	switch operate {
+	case '+':
+		return a + b
+	case '-':
+		return a - b
+	case '*':
+		return a * b
+	default:
+		panic("operate not exist")
+	}
+}
+
+func ways(input string, cache map[string][]int) []int {
+	if _, ok := cache[input]; ok {
+		return cache[input]
+	}
+
+	ans := []int{}
+
+	for i := 0; i < len(input); i++ {
+		ch := input[i]
+
+		if ch == '+' || ch == '-' || ch == '*' {
+			left := input[:i]
+			right := input[i+1:]
+
+			l := ways(left, cache)
+			r := ways(right, cache)
+
+			for _, a := range l {
+				for _, b := range r {
+					ans = append(ans, calculate(a, b, rune(ch)))
+				}
+			}
+		}
+	}
+
+	if len(ans) == 0 {
+		number, _ := strconv.Atoi(input)
+		ans = append(ans, number)
+	}
+
+	cache[input] = ans
+
+	return ans
 }
diff --git a/src/0241.Different-Ways-to-Add-Parentheses/Solution_test.go b/src/0241.Different-Ways-to-Add-Parentheses/Solution_test.go
index 673e32c5f..5cc26ff2a 100644
--- a/src/0241.Different-Ways-to-Add-Parentheses/Solution_test.go
+++ b/src/0241.Different-Ways-to-Add-Parentheses/Solution_test.go
@@ -1,7 +1,6 @@
 package Solution
 
 import (
-	"reflect"
 	"strconv"
 	"testing"
 )
@@ -21,9 +20,17 @@ func TestSolution(t *testing.T) {
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
 			got := diffWaysToCompute(c.inputs)
-			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+			if len(got) != len(c.expect) {
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v", c.expect, got, c.inputs)
+			}
+			m := make(map[int]int)
+			for v := range got {
+				m[v]++
+			}
+			for v := range c.expect {
+				if _, ok := m[v]; !ok {
+					t.Fatalf("expected: %v, but got: %v, with inputs: %v", c.expect, got, c.inputs)
+				}
 			}
 		})
 	}
diff --git a/src/0621.Task-Scheduler/Solution.go b/src/0621.Task-Scheduler/Solution.go
index 70f46222c..2e4f21583 100644
--- a/src/0621.Task-Scheduler/Solution.go
+++ b/src/0621.Task-Scheduler/Solution.go
@@ -1,8 +1,31 @@
 package Solution
 
+import "sort"
 
-
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
 
 func leastInterval(tasks []byte, n int) int {
-	return 0
+	tmp := make([]int, 26)
+	temp := []int{}
+	p := 1
+	for _, v := range tasks {
+		tmp[v-'A']++
+	}
+	for _, v := range tmp {
+		temp = append(temp, v)
+	}
+	sort.Slice(temp, func(a, b int) bool {
+		return temp[a] > temp[b]
+	})
+	for i := 1; i < len(temp); i++ {
+		if temp[0] == temp[i] {
+			p++
+		}
+	}
+	return max((n+1)*(temp[0]-1)+p, len(tasks))
 }