Merge pull request #1044 from 0xff-dev/2924

Add solution and test-cases for problem 2924

Author: 6boris

leetcode/2901-3000/2924.Find-Champion-II/1.png

@@ -1,28 +1,40 @@
 # [2924.Find Champion 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
+There are `n` teams numbered from `0` to `n - 1` in a tournament; each team is also a node in a **DAG**.
+
+You are given the integer `n` and a **0-indexed** 2D integer array `edges` of length `m` representing the **DAG**, where `edges[i] = [ui, vi]` indicates that there is a directed edge from team `ui` to team `vi` in the graph.
+
+A directed edge from `a` to `b` in the graph means that team `a` is **stronger** than team `b` and team `b` is **weaker** than team `a`.
+
+Team `a` will be the **champion** of the tournament if there is no team `b` that is **stronger** than team `a`.
+
+Return the team that will be the **champion** of the tournament if there is a **unique** champion, otherwise, return `-1`.
 
-**Example 1:**
+**Notes**
+
+- A **cycle** is a series of nodes `a1, a2, ..., an, an+1` such that node `a1` is the same node as node `an+1`, the nodes `a1, a2, ..., an` are distinct, and there is a directed edge from the node `ai` to node `ai+1` for every `i` in the range `[1, n]`.
+- A **DAG** is a directed graph that does not have any **cycle**.
+
+**Example 1:**  
+
+![1](./1.png)
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: n = 3, edges = [[0,1],[1,2]]
+Output: 0
+Explanation: Team 1 is weaker than team 0. Team 2 is weaker than team 1. So the champion is team 0.
 ```
 
-## 题意
-> ...
+**Example 2:**  
 
-## 题解
+![2](./2.png)
 
-### 思路1
-> ...
-Find Champion II
-```go
 ```
-
+Input: n = 4, edges = [[0,2],[1,3],[1,2]]
+Output: -1
+Explanation: Team 2 is weaker than team 0 and team 1. Team 3 is weaker than team 1. But team 1 and team 0 are not weaker than any other teams. So the answer is -1.
+```
 
 ## 结语
 

leetcode/2901-3000/2924.Find-Champion-II/2.png

@@ -1,5 +1,20 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(n int, edges [][]int) int {
+	in := make(map[int]int)
+	for _, e := range edges {
+		in[e[1]]++
+	}
+	ans := -1
+	cur := 0
+	for i := range n {
+		if in[i] == 0 {
+			cur++
+			ans = i
+			if cur > 1 {
+				return -1
+			}
+		}
+	}
+	return ans
 }

leetcode/2901-3000/2924.Find-Champion-II/README.md

@@ -10,30 +10,30 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		n      int
+		edges  [][]int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 3, [][]int{{0, 1}, {1, 2}}, 0},
+		{"TestCase2", 4, [][]int{{0, 2}, {1, 3}, {1, 2}}, -1},
 	}
 
 	//	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.n, c.edges)
 			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.n, c.edges)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }