Add solution and test-cases for problem 1390

leetcode/1301-1400/1390.Four-Divisors/README.md

@@ -0,0 +1,37 @@
+# [1390.Four Divisors][title]
+
+## Description
+Given an integer array `nums`, return the sum of divisors of the integers in that array that have exactly four divisors. If there is no such integer in the array, return `0`.
+
+**Example 1:**
+
+```
+Input: nums = [21,4,7]
+Output: 32
+Explanation: 
+21 has 4 divisors: 1, 3, 7, 21
+4 has 3 divisors: 1, 2, 4
+7 has 2 divisors: 1, 7
+The answer is the sum of divisors of 21 only.
+```
+
+**Example 2:**
+
+```
+Input: nums = [21,21]
+Output: 64
+```
+
+**Example 3:**
+
+```
+Input: nums = [1,2,3,4,5]
+Output: 0
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/four-divisors
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/1301-1400/1390.Four-Divisors/Solution.go

@@ -1,5 +1,35 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "math"
+
+func check(n int) (bool, int) {
+	r := 0
+	ans := 0
+	for i := 1; i <= int(math.Sqrt(float64(n))); i++ {
+		if n%i == 0 {
+			another := n / i
+			r++
+			ans += i
+			if another != i {
+				r++
+				ans += another
+			}
+			if r > 4 {
+				return false, 0
+			}
+		}
+	}
+	return r == 4, ans
+}
+
+func Solution(nums []int) int {
+	ans := 0
+	for _, n := range nums {
+		ok, v := check(n)
+		if !ok {
+			continue
+		}
+		ans += v
+	}
+	return ans
 }

leetcode/1301-1400/1390.Four-Divisors/Solution_test.go

@@ -10,12 +10,12 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs []int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{21, 4, 7}, 32},
+		{"TestCase2", []int{21, 21}, 64},
+		{"TestCase3", []int{1, 2, 3, 4, 5}, 0},
 	}
 
 	//	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() {
 }