Add solution and test-cases for problem 3508

Author: 0xff-dev

leetcode/3501-3600/3508.Implement-Router/README.md

@@ -1,28 +1,76 @@
 # [3508.Implement Router][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
+Design a data structure that can efficiently manage data packets in a network router. Each data packet consists of the following attributes:
+
+- `source`: A unique identifier for the machine that generated the packet.
+- `destination`: A unique identifier for the target machine.
+- `timestamp`: The time at which the packet arrived at the router.
+
+Implement the `Router` class:
+
+`Router(int memoryLimit)`: Initializes the Router object with a fixed memory limit.
+
+- `memoryLimit` is the **maximum** number of packets the router can store at any given time.
+- If adding a new packet would exceed this limit, the **oldest** packet must be removed to free up space.
+
+` bool addPacket(int source, int destination, int timestamp)`: Adds a packet with the given attributes to the router.
+
+- A packet is considered a duplicate if another packet with the same `source`, `destination`, and `timestamp` already exists in the router.
+- Return `true` if the packet is successfully added (i.e., it is not a duplicate); otherwise return `false`.
+
+` int[] forwardPacket()`: Forwards the next packet in FIFO (First In First Out) order.
+
+- Remove the packet from storage.
+- Return the packet as an array `[source, destination, timestamp]`.
+- If there are no packets to forward, return an empty array.
+
+`int getCount(int destination, int startTime, int endTime)`:
+
+- Returns the number of packets currently stored in the router (i.e., not yet forwarded) that have the specified destination and have timestamps in the inclusive range `[startTime, endTime]`.
+
+**Note** that queries for `addPacket` will be made in increasing order of `timestamp`.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
-```
+Input:
+["Router", "addPacket", "addPacket", "addPacket", "addPacket", "addPacket", "forwardPacket", "addPacket", "getCount"]
+[[3], [1, 4, 90], [2, 5, 90], [1, 4, 90], [3, 5, 95], [4, 5, 105], [], [5, 2, 110], [5, 100, 110]]
 
-## 题意
-> ...
+Output:
+[null, true, true, false, true, true, [2, 5, 90], true, 1]
 
-## 题解
+Explanation
 
-### 思路1
-> ...
-Implement Router
-```go
+Router router = new Router(3); // Initialize Router with memoryLimit of 3.
+router.addPacket(1, 4, 90); // Packet is added. Return True.
+router.addPacket(2, 5, 90); // Packet is added. Return True.
+router.addPacket(1, 4, 90); // This is a duplicate packet. Return False.
+router.addPacket(3, 5, 95); // Packet is added. Return True
+router.addPacket(4, 5, 105); // Packet is added, [1, 4, 90] is removed as number of packets exceeds memoryLimit. Return True.
+router.forwardPacket(); // Return [2, 5, 90] and remove it from router.
+router.addPacket(5, 2, 110); // Packet is added. Return True.
+router.getCount(5, 100, 110); // The only packet with destination 5 and timestamp in the inclusive range [100, 110] is [4, 5, 105]. Return 1.
 ```
 
+**Example 2:**
+
+```
+Input:
+["Router", "addPacket", "forwardPacket", "forwardPacket"]
+[[2], [7, 4, 90], [], []]
+
+Output:
+[null, true, [7, 4, 90], []]
+
+Explanation
+
+Router router = new Router(2); // Initialize Router with memoryLimit of 2.
+router.addPacket(7, 4, 90); // Return True.
+router.forwardPacket(); // Return [7, 4, 90].
+router.forwardPacket(); // There are no packets left, return [].
+```
 
 ## 结语
 

leetcode/3501-3600/3508.Implement-Router/Solution.go

@@ -1,5 +1,96 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import "sort"
+
+type Router struct {
+	memoryLimit int
+	queue       [][3]int
+	// source, dest, timestamp
+	in map[[3]int]struct{}
+
+	// dest: [source, timestamp]
+	dest map[int][]int
+}
+
+func Constructor(memoryLimit int) Router {
+	return Router{
+		memoryLimit: memoryLimit,
+		queue:       make([][3]int, 0),
+		in:          map[[3]int]struct{}{},
+		dest:        make(map[int][]int),
+	}
+}
+
+func (this *Router) AddPacket(source int, destination int, timestamp int) bool {
+	key := [3]int{source, destination, timestamp}
+	if _, ok := this.in[key]; ok {
+		return false
+	}
+	this.in[key] = struct{}{}
+	cur := len(this.queue)
+	if cur == this.memoryLimit {
+		_ = this.ForwardPacket()
+	}
+	this.queue = append(this.queue, key)
+
+	this.dest[destination] = append(this.dest[destination], timestamp)
+	return true
+}
+
+func (this *Router) ForwardPacket() []int {
+	if len(this.queue) == 0 {
+		return []int{}
+	}
+
+	first := this.queue[0]
+	this.queue = this.queue[1:]
+	delete(this.in, first)
+	// 同时移除队列的数据
+	sources := this.dest[first[1]]
+	index := sort.Search(len(sources), func(i int) bool {
+		return sources[i] >= first[2]
+	})
+	sources = append(sources[:index], sources[index+1:]...)
+	this.dest[first[1]] = sources
+	return first[:]
+}
+
+func (this *Router) GetCount(destination int, startTime int, endTime int) int {
+	sources, ok := this.dest[destination]
+	if !ok {
+		return 0
+	}
+	start := sort.Search(len(sources), func(i int) bool {
+		return sources[i] >= startTime
+	})
+	end := sort.Search(len(sources), func(i int) bool {
+		return sources[i] > endTime
+	})
+	return end - start
+}
+
+type op struct {
+	name                           string
+	source, destination, timestamp int
+}
+
+func Solution(memoryLimit int, ops []op) []any {
+	ret := make([]any, 0)
+	c := Constructor(memoryLimit)
+	for _, o := range ops {
+		if o.name == "add" {
+			ret = append(ret, c.AddPacket(o.source, o.destination, o.timestamp))
+			continue
+		}
+
+		if o.name == "for" {
+			ret = append(ret, c.ForwardPacket())
+			continue
+		}
+
+		if o.name == "get" {
+			ret = append(ret, c.GetCount(o.source, o.destination, o.timestamp))
+		}
+	}
+	return ret
 }

leetcode/3501-3600/3508.Implement-Router/Solution_test.go

@@ -10,30 +10,42 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs int
+		ops    []op
+		expect []any
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 3, []op{
+			{"add", 1, 4, 90},
+			{"add", 2, 5, 90},
+			{"add", 1, 4, 90},
+			{"add", 3, 5, 95},
+			{"add", 4, 5, 105},
+			{"for", 0, 0, 0},
+			{"add", 5, 2, 110},
+			{"get", 5, 100, 110},
+		}, []any{true, true, false, true, true, []int{2, 5, 90}, true, 1}},
+
+		{"TestCase12", 2, []op{
+			{"add", 7, 4, 90}, {"for", 0, 0, 0}, {"for", 0, 0, 0},
+		}, []any{true, []int{7, 4, 90}, []int{}}},
 	}
 
 	//	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.ops)
 			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.ops)
 			}
 		})
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }