feat: add js/ts solutions to lc problem: No.0260 (doocs#3383)

Author: rain84

solution/0200-0299/0260.Single Number III/README.md

@@ -238,4 +238,48 @@ public class Solution {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### 方法二：哈希表
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+function singleNumber(nums: number[]): number[] {
+    const set = new Set<number>();
+
+    for (const x of nums) {
+        if (set.has(x)) set.delete(x);
+        else set.add(x);
+    }
+
+    return [...set];
+}
+```
+
+#### JavaScript
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+function singleNumber(nums) {
+    const set = new Set();
+
+    for (const x of nums) {
+        if (set.has(x)) set.delete(x);
+        else set.add(x);
+    }
+
+    return [...set];
+}
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->

solution/0200-0299/0260.Single Number III/README_EN.md

@@ -236,4 +236,48 @@ public class Solution {
 
 <!-- solution:end -->
 
+<!-- solution:start -->
+
+### Solution 2: Hash Table
+
+<!-- tabs:start -->
+
+#### TypeScript
+
+```ts
+function singleNumber(nums: number[]): number[] {
+    const set = new Set<number>();
+
+    for (const x of nums) {
+        if (set.has(x)) set.delete(x);
+        else set.add(x);
+    }
+
+    return [...set];
+}
+```
+
+#### JavaScript
+
+```js
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+function singleNumber(nums) {
+    const set = new Set();
+
+    for (const x of nums) {
+        if (set.has(x)) set.delete(x);
+        else set.add(x);
+    }
+
+    return [...set];
+}
+```
+
+<!-- tabs:end -->
+
+<!-- solution:end -->
+
 <!-- problem:end -->

solution/0200-0299/0260.Single Number III/Solution2.js

@@ -0,0 +1,14 @@
+/**
+ * @param {number[]} nums
+ * @return {number[]}
+ */
+function singleNumber(nums) {
+    const set = new Set();
+
+    for (const x of nums) {
+        if (set.has(x)) set.delete(x);
+        else set.add(x);
+    }
+
+    return [...set];
+}

solution/0200-0299/0260.Single Number III/Solution2.ts

@@ -0,0 +1,10 @@
+function singleNumber(nums: number[]): number[] {
+    const set = new Set<number>();
+
+    for (const x of nums) {
+        if (set.has(x)) set.delete(x);
+        else set.add(x);
+    }
+
+    return [...set];
+}