Add solution and test-cases for problem 1780

Author: 0xff-dev

leetcode/1701-1800/1780.Check-if-Number-is-a-Sum-of-Powers-of-Three/README.md

@@ -1,28 +1,32 @@
 # [1780.Check if Number is a Sum of Powers of Three][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+Given an integer `n`, return `true` if it is possible to represent `n` as the sum of distinct powers of three. Otherwise, return `false`.
+
+An integer `y` is a power of three if there exists an integer `x` such that `y == 3^x`.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: n = 12
+Output: true
+Explanation: 12 = 31 + 32
 ```
 
-## 题意
-> ...
+**Example 2:**
 
-## 题解
-
-### 思路1
-> ...
-Check if Number is a Sum of Powers of Three
-```go
+```
+Input: n = 91
+Output: true
+Explanation: 91 = 30 + 32 + 34
 ```
 
+**Example 3:**
+
+```
+Input: n = 21
+Output: false
+```
 
 ## 结语
 

leetcode/1701-1800/1780.Check-if-Number-is-a-Sum-of-Powers-of-Three/Solution.go

@@ -1,5 +1,21 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(n int) bool {
+	arr := make([]int, 15)
+	arr[0] = 1
+	for i := 1; i < 15; i++ {
+		arr[i] = arr[i-1] * 3
+	}
+	var ok func(int, int) bool
+	ok = func(index, cur int) bool {
+		if cur == 0 {
+			return true
+		}
+		if index == 15 {
+			return false
+		}
+
+		return ok(index+1, cur-arr[index]) || ok(index+1, cur)
+	}
+	return ok(0, n)
 }

leetcode/1701-1800/1780.Check-if-Number-is-a-Sum-of-Powers-of-Three/Solution_test.go

@@ -10,12 +10,12 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
+		inputs int
 		expect bool
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 12, true},
+		{"TestCase2", 91, true},
+		{"TestCase3", 21, false},
 	}
 
 	//	开始测试
@@ -30,10 +30,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }