powx-n/

Author: masx200

README.md

@@ -24,6 +24,8 @@ https://leetcode-cn.com/problems/fibonacci-number/
 
 https://leetcode-cn.com/problems/merge-sorted-array/
 
+https://leetcode-cn.com/problems/powx-n/
+
 #### 安装教程
 
 1. 安装`deno`

deno.json

@@ -1,4 +1,7 @@
 {
+    "compilerOptions": {
+        "strict": true
+    },
     "importMap": "import_map.json",
     "tasks": {
         "udd": "udd '*.ts'",

deps.ts

@@ -1,7 +1,7 @@
-import {
+export {
     assert,
+    assertAlmostEquals,
     assertEquals,
     assertStrictEquals,
     equal,
 } from "https://deno.land/[email protected]/testing/asserts.ts";
-export { assert, assertEquals, assertStrictEquals, equal };

mod.ts

@@ -1,4 +1,5 @@
 import mergeSortedArray from "./merge-sorted-array/index.ts";
+import pow_x_n from "./powx-n/index.ts";
 
 import htmlEntityParser from "./html-entity-parser/index.ts";
 
@@ -8,7 +9,7 @@ export {
     ListNodeToArray,
 } from "./reverse-linked-list/index.ts";
 import reverseLinkedList from "./reverse-linked-list/index.ts";
-
+export { pow_x_n };
 import climbStairs from "./climbing-stairs/index.ts";
 import fei_bo_na_qi_shu_lie_lcof from "./fei-bo-na-qi-shu-lie-lcof/index.ts";
 

powx-n/index.ts

@@ -0,0 +1,55 @@
+export default function myPow(x: number, n: number): number {
+    if (Number.isNaN(x) || Number.isNaN(n)) {
+        throw Error("nan:" + x + "," + n);
+    }
+    if (!Number.isFinite(x) || !Number.isFinite(n)) {
+        throw Error("InFinite:" + x + "," + n);
+    }
+    setTimeout(() => {
+        cacheStore.clear();
+    }, 0);
+    const cached = cacheStore.get(`${x},${n}`);
+    if (cached) {
+        return cached;
+    }
+    // console.log(x,n)
+    const result = n === 1
+        ? x
+        : x < 0
+        ? (n % 2 === 0 ? 1 : -1) * myPow(-x, n)
+        : x === 1
+        ? 1
+        : x === 0
+        ? 0
+        : n === 0
+        ? 1
+        : n < 0
+        ? myPow(1 / x, -n)
+        : n % 2
+        ? lazyMultiplyPositive(
+            () => x,
+            () => myPow(x, n - 1),
+        )
+        : lazyMultiplyPositive(
+            () => myPow(x, Math.floor(n / 2)),
+            () => myPow(x, n - Math.floor(n / 2)),
+        );
+    cacheStore.set(`${x},${n}`, result);
+    return result;
+}
+
+const cacheStore = new Map<`${number},${number}`, number>();
+
+function lazyMultiplyPositive(a: () => number, b: () => number): number {
+    if (Math.random() < 0.5) {
+        [b, a] = [a, b];
+    }
+    const l = a();
+    if (l === 0) {
+        return 0;
+    } else if (l === Infinity) {
+        return Infinity;
+    } else {
+        return l * b();
+    }
+}

powx-n/test.ts

@@ -0,0 +1,27 @@
+import { assertAlmostEquals } from "../deps.ts";
+import { pow_x_n } from "../mod.ts";
+
+Deno.test("powx-n", () => {
+    const examples: {
+        input: Parameters<typeof pow_x_n>;
+        output: ReturnType<typeof pow_x_n>;
+    }[] = [
+        { input: [2.0, 10], output: 1024.0 },
+        { input: [2.1, 3], output: 9.261 },
+        { input: [2.0, -2], output: 0.25 },
+        {
+            input: [2, 6],
+            output: 64.0,
+        },
+        { input: [2, -99999], output: 0.0 },
+        { input: [6553688888888, 6553688888888], output: Infinity },
+        { input: [6553688888888, -6553688888888], output: 0.0 },
+        { input: [1 / 6553688888888, 6553688888888], output: 0.0 },
+        { input: [1 / 6553688888888, -6553688888888], output: Infinity },
+        { input: [-6553688888888, -6553688888888], output: 0.0 },
+        { input: [-6553688888888, 6553688888888], output: Infinity },
+    ];
+    examples.forEach(({ input, output }) => {
+        assertAlmostEquals(output, pow_x_n(...input));
+    });
+});