feat: add Group Anagrams

Author: dukeluo

README.md

@@ -4,10 +4,9 @@ https://neetcode.io/roadmap
 
 ### Leetcode
 
-<!-- create a table for me -->
-
 | #   | Title                                                                   | Difficulty | Solution                                             |
 | --- | ----------------------------------------------------------------------- | ---------- | ---------------------------------------------------- |
 | 217 | [Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | Easy       | [TypeScript](./TypeScript/217.contains-duplicate.ts) |
 | 242 | [Valid Anagram](https://leetcode.com/problems/valid-anagram/)           | Easy       | [TypeScript](./TypeScript/242.valid-anagram.ts)      |
 | 242 | [Two Sum](https://leetcode.com/problems/two-sum/)                       | Easy       | [TypeScript](./TypeScript/1.two-sum.ts)              |
+| 49  | [Group Anagrams](https://leetcode.com/problems/two-sum/)                | Medium     | [TypeScript](./TypeScript/49.group-anagrams.ts)      |

TypeScript/49.group-anagrams.ts

@@ -0,0 +1,19 @@
+function groupAnagrams(strs: string[]): string[][] {
+  const map = new Map<string, string[]>();
+
+  strs.forEach((s) => {
+    const identity = new Array(26).fill(0); // it also can be the sorted string
+
+    for (let i = 0; i < s.length; i++) {
+      identity[s.charCodeAt(i) - 97] += 1;
+    }
+
+    const key = identity.join(",");
+    const anagrams = map.get(key) ?? [];
+
+    anagrams.push(s);
+    map.set(key, anagrams);
+  });
+
+  return Array.from(map.values());
+}