Add solution and test-cases for problem 1311

leetcode/1301-1400/1311.Get-Watched-Videos-by-Your-Friends/README.md

@@ -1,28 +1,36 @@
 # [1311.Get Watched Videos by Your Friends][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
+There are `n` people, each person has a unique id between `0` and `n-1`. Given the arrays `watchedVideos` and `friends`, where `watchedVideos[i]` and `friends[i]` contain the list of watched videos and the list of friends respectively for the person with `id = i`.
+
+Level **1** of videos are all watched videos by your friends, level **2** of videos are all watched videos by the friends of your friends and so on. In general, the level `k` of videos are all watched videos by people with the shortest path **exactly** equal to `k` with you. Given your `id` and the `level` of videos, return the list of videos ordered by their frequencies (increasing). For videos with the same frequency order them alphabetically from least to greatest. 
+
+**Example 1:**  
 
-**Example 1:**
+![1](./1.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: watchedVideos = [["A","B"],["C"],["B","C"],["D"]], friends = [[1,2],[0,3],[0,3],[1,2]], id = 0, level = 1
+Output: ["B","C"] 
+Explanation: 
+You have id = 0 (green color in the figure) and your friends are (yellow color in the figure):
+Person with id = 1 -> watchedVideos = ["C"] 
+Person with id = 2 -> watchedVideos = ["B","C"] 
+The frequencies of watchedVideos by your friends are: 
+B -> 1 
+C -> 2
 ```
 
-## 题意
-> ...
+**Example 2:**  
 
-## 题解
+![2](./2.png)
 
-### 思路1
-> ...
-Get Watched Videos by Your Friends
-```go
 ```
-
+Input: watchedVideos = [["A","B"],["C"],["B","C"],["D"]], friends = [[1,2],[0,3],[0,3],[1,2]], id = 0, level = 2
+Output: ["D"]
+Explanation: 
+You have id = 0 (green color in the figure) and the only friend of your friends is the person with id = 3 (yellow color in the figure).
+```
 
 ## 结语
 

leetcode/1301-1400/1311.Get-Watched-Videos-by-Your-Friends/Solution.go

@@ -1,5 +1,42 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+func Solution(watchedVideos [][]string, friends [][]int, id int, level int) []string {
+	now := 0
+	var ans []string
+	queue := []int{id}
+	visited := [100]bool{}
+	visited[id] = true
+	for ; now < level; now++ {
+		nq := make([]int, 0)
+		videos := map[string]int{}
+		next := make([]string, 0)
+		for _, u := range queue {
+			for _, f := range friends[u] {
+				if visited[f] {
+					continue
+				}
+				visited[f] = true
+				nq = append(nq, f)
+				for _, w := range watchedVideos[f] {
+					videos[w]++
+				}
+			}
+		}
+		for v := range videos {
+			next = append(next, v)
+		}
+		sort.Slice(next, func(i, j int) bool {
+			a, b := videos[next[i]], videos[next[j]]
+			if a == b {
+				return next[i] < next[j]
+			}
+			return a < b
+		})
+		ans = next
+		queue = nq
+	}
+	return ans
+
 }

leetcode/1301-1400/1311.Get-Watched-Videos-by-Your-Friends/Solution_test.go

@@ -9,31 +9,32 @@ import (
 func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
-		name   string
-		inputs bool
-		expect bool
+		name          string
+		watchedVideos [][]string
+		friends       [][]int
+		id, level     int
+		expect        []string
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", [][]string{{"A", "B"}, {"C"}, {"B", "C"}, {"D"}}, [][]int{{1, 2}, {0, 3}, {0, 3}, {1, 2}}, 0, 1, []string{"B", "C"}},
+		{"TestCase2", [][]string{{"A", "B"}, {"C"}, {"B", "C"}, {"D"}}, [][]int{{1, 2}, {0, 3}, {0, 3}, {1, 2}}, 0, 2, []string{"D"}},
 	}
 
 	//	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.watchedVideos, c.friends, c.id, c.level)
 			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 %v %v",
+					c.expect, got, c.watchedVideos, c.friends, c.id, c.level)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }