Create 3508-implement-router.js

Author: everthis

3508-implement-router.js

@@ -0,0 +1,96 @@
+class Router {
+    constructor(memoryLimit) {
+        this.memoryLimit = memoryLimit;
+        this.storage = [];
+        this.packetSet = new Set();
+        this.destMap = new Map();
+    }
+
+    addPacket(source, destination, timestamp) {
+        const packet = [source, destination, timestamp];
+        if (this.packetSet.has(packet.toString())) {
+            return false;
+        }
+
+        if (this.storage.length >= this.memoryLimit) {
+            this._removeOldest();
+        }
+
+        this.storage.push(packet);
+        this.packetSet.add(packet.toString());
+
+        if (!this.destMap.has(destination)) {
+            this.destMap.set(destination, []);
+        }
+
+        this.destMap.get(destination).push(timestamp);
+        return true;
+    }
+
+    forwardPacket() {
+        if (this.storage.length === 0) {
+            return [];
+        }
+
+        const packet = this.storage.shift();
+        const [source, destination, timestamp] = packet;
+        this.packetSet.delete(packet.toString());
+
+        const tsList = this.destMap.get(destination);
+        const idx = this._binarySearch(tsList, timestamp);
+        if (idx < tsList.length && tsList[idx] === timestamp) {
+            tsList.splice(idx, 1);
+        }
+
+        if (tsList.length === 0) {
+            this.destMap.delete(destination);
+        }
+
+        return [source, destination, timestamp];
+    }
+
+    getCount(destination, startTime, endTime) {
+        if (!this.destMap.has(destination)) {
+            return 0;
+        }
+
+        const tsList = this.destMap.get(destination);
+        const leftIndex = this._binarySearch(tsList, startTime);
+        const rightIndex = this._binarySearch(tsList, endTime, true);
+        return rightIndex - leftIndex;
+    }
+
+    _removeOldest() {
+        if (this.storage.length > 0) {
+            const packet = this.storage.shift();
+            const [source, destination, timestamp] = packet;
+            this.packetSet.delete(packet.toString());
+
+            const tsList = this.destMap.get(destination);
+            const idx = this._binarySearch(tsList, timestamp);
+            if (idx < tsList.length && tsList[idx] === timestamp) {
+                tsList.splice(idx, 1);
+            }
+
+            if (tsList.length === 0) {
+                this.destMap.delete(destination);
+            }
+        }
+    }
+
+    _binarySearch(arr, target, isRight = false) {
+        let left = 0;
+        let right = arr.length;
+
+        while (left < right) {
+            const mid = Math.floor((left + right) / 2);
+            if (arr[mid] < target || (isRight && arr[mid] === target)) {
+                left = mid + 1;
+            } else {
+                right = mid;
+            }
+        }
+
+        return left;
+    }
+}