https://leetcode.cn/problems/tweet-counts-per-frequency/

Author: masx200

README.md

@@ -844,6 +844,8 @@ https://leetcode.cn/problems/1-bit-and-2-bit-characters/
 
 https://leetcode.cn/problems/design-twitter/
 
+https://leetcode.cn/problems/tweet-counts-per-frequency/
+
 #### 安装教程
 
 1. 安装`deno`

deps.ts

@@ -16,6 +16,8 @@ export { walk } from "https://deno.land/[email protected]/fs/mod.ts";
 export { parse } from "https://deno.land/[email protected]/flags/mod.ts";
 export { combinations } from "https://deno.land/x/[email protected]/mod.ts";
 export { isIP } from "https://deno.land/[email protected]/node/internal/net.ts";
+export { Heap } from "https://cdn.skypack.dev/@datastructures-js/[email protected]/?dts";
 export {
-    Heap,
-} from "https://cdn.skypack.dev/@datastructures-js/[email protected]/?dts";
+    BinarySearchTree,
+    BinarySearchTreeNode,
+} from "https://cdn.skypack.dev/@datastructures-js/[email protected]/?dts";

design-twitter/index.ts

@@ -51,8 +51,8 @@ export default class Twitter {
     }
 
     follow(followerId: number, followeeId: number): void {
-        const followee =
-            this.#follower_to_followees.get(followerId) ?? new Set();
+        const followee = this.#follower_to_followees.get(followerId) ??
+            new Set();
 
         followee.add(followeeId);
         this.#follower_to_followees.set(followerId, followee);

tweet-counts-per-frequency/index.ts

@@ -0,0 +1,72 @@
+import { BinarySearchTree, BinarySearchTreeNode } from "../deps.ts";
+
+export default class TweetCounts {
+    #name_to_bst = new Map<string, BinarySearchTree<number, number>>();
+    constructor() {}
+
+    recordTweet(tweetName: string, time: number): void {
+        const bst = this.#name_to_bst.get(tweetName) ??
+            new BinarySearchTree<number, number>();
+        const node = bst.find(time);
+        if (node) {
+            node.setValue(node.getValue() + 1);
+            return;
+        }
+        bst.insert(time, 1);
+        this.#name_to_bst.set(tweetName, bst);
+    }
+
+    getTweetCountsPerFrequency(
+        freq: string,
+        tweetName: string,
+        startTime: number,
+        endTime: number,
+    ): number[] {
+        const bst = this.#name_to_bst.get(tweetName);
+        if (!bst) return [];
+        const length = freq === "minute"
+            ? 60
+            : freq === "hour"
+            ? 3600
+            : freq === "day"
+            ? 86400
+            : 0;
+        if (length === 0) {
+            throw Error("invalid frequency");
+        }
+        const result: number[] = Array(
+            Math.ceil((endTime - startTime + 1) / length),
+        ).fill(0);
+        traversal_bst_range(
+            bst.root(),
+            startTime,
+            endTime,
+            (num: number, value: number) => {
+                result[Math.floor((num - startTime + 1) / length)] += value;
+            },
+        );
+        return result;
+    }
+}
+export function traversal_bst_range<
+    K extends string | number = number,
+    V = number,
+>(
+    node: BinarySearchTreeNode<K, V> | null | undefined,
+    low: number,
+    high: number,
+    callback: (key: K, value: V) => void,
+) {
+    if (!node) return;
+
+    const value = node.getKey();
+    if (value <= high && value >= low) {
+        callback(value, node.getValue());
+    }
+    if (value > low) {
+        traversal_bst_range(node.getLeft(), low, high, callback);
+    }
+    if (value < high) {
+        traversal_bst_range(node.getRight(), low, high, callback);
+    }
+}