Merge pull request #1245 from 0xff-dev/2014

Add solution and test-cases for problem 2014

Author: 6boris

leetcode/2001-2100/2014.Longest-Subsequence-Repeated-k-Times/1.png

@@ -1,28 +1,43 @@
 # [2014.Longest Subsequence Repeated k Times][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
 
-**Example 1:**
+You are given a string `s` of length `n`, and an integer `k`. You are tasked to find the **longest subsequence repeated** `k` times in string `s`.
+
+A **subsequence** is a string that can be derived from another string by deleting some or no characters without changing the order of the remaining characters.
+
+A subsequence `seq` is **repeated** `k` times in the string `s` if `seq * k` is a subsequence of `s`, where `seq * k` represents a string constructed by concatenating `seq k` times.
+
+- For example, `"bba"` is repeated `2` times in the string `"bababcba"`, because the string `"bbabba"`, constructed by concatenating `"bba"` `2` times, is a subsequence of the string `"bababcba"`.
+
+Return the **longest subsequence repeated** `k` times in string `s`. If multiple such subsequences are found, return the **lexicographicall6 largest** one. If there is no such subsequence, return an **empty** string.
+
+**Example 1:**  
+
+![1](./1.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: s = "letsleetcode", k = 2
+Output: "let"
+Explanation: There are two longest subsequences repeated 2 times: "let" and "ete".
+"let" is the lexicographically largest one.
 ```
 
-## 题意
-> ...
-
-## 题解
+**Example 2:**
 
-### 思路1
-> ...
-Longest Subsequence Repeated k Times
-```go
+```
+Input: s = "bb", k = 2
+Output: "b"
+Explanation: The longest subsequence repeated 2 times is "b".
 ```
 
+**Example 3:**
+
+```
+Input: s = "ab", k = 2
+Output: ""
+Explanation: There is no subsequence repeated 2 times. Empty string is returned.
+```
 
 ## 结语
 

leetcode/2001-2100/2014.Longest-Subsequence-Repeated-k-Times/README.md

@@ -1,5 +1,54 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(s string, k int) string {
+	count := [26]int{}
+	for _, b := range s {
+		count[b-'a']++
+	}
+	var greaterK []string
+	for i := 25; i >= 0; i-- {
+		if count[i] >= k {
+			greaterK = append(greaterK, string('a'+byte(i)))
+		}
+	}
+
+	var match func(string) bool
+	match = func(pattern string) bool {
+		i, c := 0, 0
+		for j := 0; j < len(s); j++ {
+			if s[j] == pattern[i] {
+				i++
+				if i == len(pattern) {
+					c++
+					i = 0
+					if c >= k {
+						return true
+					}
+				}
+			}
+		}
+		return false
+	}
+
+	loop := make([]string, len(greaterK))
+	copy(loop, greaterK)
+	// z, y, x, 我们应该需要判断 z ok (zz) ok , zzz(ok) / 以及 zx, zy ...
+	var ans string
+	for len(loop) > 0 {
+		cur := loop[0]
+		loop = loop[1:]
+		if len(cur) > len(ans) {
+			ans = cur
+		}
+		// 开始做组合
+		for _, p := range greaterK {
+			pattern := cur + p
+			if match(pattern) {
+				// 这个匹配后，我们需要判断是否还可以继续与其他的z,y x这种组合
+				loop = append(loop, pattern)
+			}
+		}
+	}
+
+	return ans
 }

leetcode/2001-2100/2014.Longest-Subsequence-Repeated-k-Times/Solution.go

@@ -10,30 +10,31 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs string
+		k      int
+		expect string
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", "letsleetcode", 2, "let"},
+		{"TestCase2", "bb", 2, "b"},
+		{"TestCase3", "ab", 2, ""},
 	}
 
 	//	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() {
 }