Merge pull request #1262 from 0xff-dev/3202

Add solution and test-cases for proble 3202

Author: 6boris

leetcode/3201-3300/3202.Find-the-Maximum-Length-of-Valid-Subsequence-II/README.md

@@ -1,28 +1,36 @@
 # [3202.Find the Maximum Length of Valid Subsequence II][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
+You are given an integer array `nums` and a **positive** integer `k`.
+A `subsequence` `sub` of `nums` with length `x` is called **valid** if it satisfies:
+
+- `(sub[0] + sub[1]) % k == (sub[1] + sub[2]) % k == ... == (sub[x - 2] + sub[x - 1]) % k`.
+
+Return the length of the **longest valid** subsequence of `nums`.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
-```
+Input: nums = [1,2,3,4,5], k = 2
+
+Output: 5
 
-## 题意
-> ...
+Explanation:
 
-## 题解
+The longest valid subsequence is [1, 2, 3, 4, 5].
+```
+
+**Example 2:**
 
-### 思路1
-> ...
-Find the Maximum Length of Valid Subsequence II
-```go
 ```
+Input: nums = [1,4,2,3,1,4], k = 3
+
+Output: 4
 
+Explanation:
+
+The longest valid subsequence is [1, 4, 1, 4].
+```
 
 ## 结语
 

leetcode/3201-3300/3202.Find-the-Maximum-Length-of-Valid-Subsequence-II/Solution.go

@@ -1,5 +1,54 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func longestAlternatingSubsequnece(l1, l2 []int) int {
+	a, b := 0, 0
+	ai, bi := 0, 0
+	for ai < len(l1) && bi < len(l2) {
+		if l1[ai] < l2[bi] {
+			ai++
+			a = b + 1
+			continue
+		}
+		b = a + 1
+		bi++
+	}
+	return max(a, b) + 1
+}
+func Solution(nums []int, k int) int {
+	group := make([][]int, k)
+	for i := range nums {
+		nums[i] %= k
+		group[nums[i]] = append(group[nums[i]], i)
+	}
+	// 1,0,1,0,1
+	ans, l := 0, len(nums)
+	sums := make(map[int]struct{})
+	for i := 0; i < l; i++ {
+		for j := i + 1; j < l; j++ {
+			sums[nums[i]+nums[j]] = struct{}{}
+		}
+	}
+
+	for sum := range sums {
+		used := map[int]struct{}{}
+		for i := 0; i < l; i++ {
+			if _, ok := used[nums[i]]; ok {
+				continue
+			}
+			used[nums[i]] = struct{}{}
+			target := (k + sum - nums[i]) % k
+			used[target] = struct{}{}
+
+			ll := len(group[target])
+			if ll == 0 {
+				continue
+			}
+			if nums[i] == target {
+				ans = max(ans, ll)
+				continue
+			}
+			ans = max(ans, longestAlternatingSubsequnece(group[nums[i]], group[target]))
+		}
+	}
+	return ans
 }

leetcode/3201-3300/3202.Find-the-Maximum-Length-of-Valid-Subsequence-II/Solution_test.go

@@ -10,30 +10,30 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs []int
+		k      int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", []int{1, 2, 3, 4, 5}, 2, 5},
+		{"TestCase2", []int{1, 4, 2, 3, 1, 4}, 3, 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.inputs, 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.inputs, 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() {
 }