Add solution and test-cases for problem 689

Author: 0xff-dev

leetcode/601-700/0689.Maximum-Sum-of-3-Non-Overlapping-Subarrays/README.md

@@ -1,28 +1,25 @@
 # [689.Maximum Sum of 3 Non-Overlapping Subarrays][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 array `nums` and an integer `k`, find three non-overlapping subarrays of length `k` with maximum sum and return them.
+
+Return the result as a list of indices representing the starting position of each interval (**0-indexed**). If there are multiple answers, return the lexicographically smallest one.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: nums = [1,2,1,2,6,7,5,1], k = 2
+Output: [0,3,5]
+Explanation: Subarrays [1, 2], [2, 6], [7, 5] correspond to the starting indices [0, 3, 5].
+We could have also taken [2, 1], but an answer of [1, 3, 5] would be lexicographically larger.
 ```
 
-## 题意
-> ...
-
-## 题解
+**EXample 2:**
 
-### 思路1
-> ...
-Maximum Sum of 3 Non-Overlapping Subarrays
-```go
 ```
-
+Input: nums = [1,2,1,2,1,2,1,2,1], k = 2
+Output: [0,2,4]
+```
 
 ## 结语
 

leetcode/601-700/0689.Maximum-Sum-of-3-Non-Overlapping-Subarrays/Solution.go

@@ -1,5 +1,39 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(nums []int, k int) []int {
+	l := len(nums)
+	sl := l - k + 1
+	sum := make([]int64, sl)
+	cur := int64(0)
+	i := 0
+	for ; i < k; i++ {
+		cur += int64(nums[i])
+	}
+	sum[0] = cur
+	for ; i < l; i++ {
+		cur -= int64(nums[i-k])
+		cur += int64(nums[i])
+		sum[i-k+1] = cur
+	}
+	maxIndex := make([]int, sl)
+	maxIndex[sl-1] = sl - 1
+	for i := sl - 2; i >= 0; i-- {
+		maxIndex[i] = maxIndex[i+1]
+		if sum[i] >= sum[maxIndex[i+1]] {
+			maxIndex[i] = i
+		}
+	}
+	m := int64(0)
+	ans := make([]int, 3)
+	for i := 0; i < l; i++ {
+		for j := i + k; j < sl-k; j++ {
+			s := sum[i] + sum[j] + sum[maxIndex[j+k]]
+			if s > m {
+				ans[0], ans[1], ans[2] = i, j, maxIndex[j+k]
+				m = s
+			}
+		}
+	}
+
+	return ans
 }

leetcode/601-700/0689.Maximum-Sum-of-3-Non-Overlapping-Subarrays/Solution_test.go

@@ -10,30 +10,31 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		nums   []int
+		k      int
+		expect []int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{1, 2, 1, 2, 6, 7, 5, 1}, 2, []int{0, 3, 5}},
+		{"TestCase2", []int{1, 2, 1, 2, 1, 2, 1, 2, 1}, 2, []int{0, 2, 4}},
+		{"TestCase3", []int{4, 5, 10, 6, 11, 17, 4, 11, 1, 3}, 1, []int{4, 5, 7}},
 	}
 
 	//	开始测试
 	for i, c := range cases {
 		t.Run(c.name+" "+strconv.Itoa(i), func(t *testing.T) {
-			got := Solution(c.inputs)
+			got := Solution(c.nums, c.k)
 			if !reflect.DeepEqual(got, c.expect) {
-				t.Fatalf("expected: %v, but got: %v, with inputs: %v",
-					c.expect, got, c.inputs)
+				t.Fatalf("expected: %v, but got: %v, with inputs: %v %v",
+					c.expect, got, c.nums, c.k)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }