Add solution and test-cases for problem 2779

leetcode/2701-2800/2779.Maximum-Beauty-of-an-Array-After-Applying-Operation/README.md

@@ -0,0 +1,45 @@
+# [2779.Maximum Beauty of an Array After Applying Operation][title]
+
+## Description
+You are given a **0-indexed** array nums and a **non-negative** integer `k`.
+
+In one operation, you can do the following:
+
+- Choose an index `i` that **hasn't been chosen before** from the range `[0, nums.length - 1]`.
+- Replace `nums[i]` with any integer from the range `[nums[i] - k, nums[i] + k]`.
+
+The **beauty** of the array is the length of the longest subsequence consisting of equal elements.
+
+Return the **maximum** possible beauty of the array `nums` after applying the operation any number of times.
+
+**Note** that you can apply the operation to each index **only once**.
+
+A **subsequence** of an array is a new array generated from the original array by deleting some elements (possibly none) without changing the order of the remaining elements.
+
+**Example 1:**
+
+```
+Input: nums = [4,6,1,2], k = 2
+Output: 3
+Explanation: In this example, we apply the following operations:
+- Choose index 1, replace it with 4 (from range [4,8]), nums = [4,4,1,2].
+- Choose index 3, replace it with 4 (from range [0,4]), nums = [4,4,1,4].
+After the applied operations, the beauty of the array nums is 3 (subsequence consisting of indices 0, 1, and 3).
+It can be proven that 3 is the maximum possible length we can achieve.
+```
+
+**Example 2:**
+
+```
+Input: nums = [1,1,1,1], k = 10
+Output: 4
+Explanation: In this example we don't have to apply any operations.
+The beauty of the array nums is 4 (whole array).
+```
+
+## 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/maximum-beauty-of-an-array-after-applying-operation
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/2701-2800/2779.Maximum-Beauty-of-an-Array-After-Applying-Operation/Solution.go

@@ -1,5 +1,39 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+func Solution(nums []int, k int) int {
+	sort.Ints(nums)
+	ans := 0
+	start, end := 0, 0
+	// 排序以后，能够出现交集的情况就是
+	// 最小的元素定义了右边界
+	// 最大的元素定义了左边界
+	// re 就是交集的右边界
+	re := nums[0] + k
+
+	for ; end < len(nums); end++ {
+		// 还在同一个范围
+		s := nums[end] - k
+		if s <= re {
+			// 还有可以增加de
+			continue
+		}
+		diff := end - start
+		ans = max(ans, diff)
+
+		// 开始减少左侧的数据
+		// 尝试移除start
+		start++
+		for ; start <= end; start++ {
+			re = nums[start] + k
+			if s <= re {
+				break
+			}
+		}
+	}
+	diff := end - start
+	ans = max(ans, diff)
+
+	return ans
 }

leetcode/2701-2800/2779.Maximum-Beauty-of-an-Array-After-Applying-Operation/Solution_test.go

@@ -10,30 +10,30 @@ 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{4, 6, 1, 2}, 2, 3},
+		{"TestCase2", []int{1, 1, 1, 1}, 10, 4},
 	}
 
 	//	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() {
 }