https://leetcode.cn/problems/rank-from-stream-lcci/

Author: masx200

README.md

@@ -10,6 +10,8 @@ leetcode 测试
 
 ##### 包含的内容如下
 
+https://leetcode.cn/problems/rank-from-stream-lcci/
+
 https://leetcode.cn/problems/minimum-cost-to-hire-k-workers/
 
 https://leetcode.cn/problems/number-of-closed-islands/

range-sum-query-2d-mutable/index.ts

@@ -41,6 +41,6 @@ export default class NumMatrix {
         return sum;
     }
 }
-function lowbit(a: number) {
+export function lowbit(a: number) {
     return a & -a;
 }

rank-from-stream-lcci/index.ts

@@ -0,0 +1,33 @@
+export default class StreamRank {
+    #bit = new BinaryIndexTree(50002);
+    constructor() {}
+
+    track(x: number): void {
+        this.#bit.change(x + 1, 1);
+    }
+
+    getRankOfNumber(x: number): number {
+        return this.#bit.query(x + 1);
+    }
+}
+export class BinaryIndexTree {
+    static lowbit(x: number) {
+        return x & -x;
+    }
+    #tree: number[];
+    constructor(public size: number) {
+        this.#tree = Array(size).fill(0);
+    }
+    change(i: number, x: number) {
+        for (let p = i; p < this.size; p += BinaryIndexTree.lowbit(p)) {
+            this.#tree[p] += x;
+        }
+    }
+    query(n: number) {
+        let ans = 0;
+        for (let p = n; p > 0; p -= BinaryIndexTree.lowbit(p)) {
+            ans += this.#tree[p];
+        }
+        return ans;
+    }
+}