feat: add Subsets II

Author: dukeluo

README.md

@@ -74,6 +74,7 @@ Roadmap: https://neetcode.io/roadmap
 | 46   | [Permutations](https://leetcode.com/problems/permutations/)                                                                                                       | Medium     | [ts](./TypeScript/46.permutations.ts)                                                         | Backtracking     |
 | 78   | [Subsets](https://leetcode.com/problems/subsets/description/)                                                                                                     | Medium     | [ts](./TypeScript/78.subsets.ts)                                                              | Backtracking     |
 | 39   | [Combination Sum](https://leetcode.com/problems/combination-sum/description/)                                                                                     | Medium     | [ts](./TypeScript/39.combination-sum.ts)                                                      | Backtracking     |
+| 90   | [Subsets II](https://leetcode.com/problems/subsets-ii/description/)                                                                                               | Medium     | [ts](./TypeScript/90.subsets-ii.ts)                                                           | Backtracking     |
 
 ### Others
 

TypeScript/90.subsets-ii.ts

@@ -0,0 +1,26 @@
+function subsetsWithDup(nums: number[]): number[][] {
+  const subsets = [];
+
+  function dfs(index: number, subset: number[]) {
+    if (index === nums.length) {
+      subsets.push(subset.slice());
+      return;
+    }
+
+    subset.push(nums[index]);
+    dfs(index + 1, subset);
+    subset.pop();
+
+    while (index + 1 < nums.length && nums[index] === nums[index + 1]) {
+      index += 1;
+    }
+    dfs(index + 1, subset);
+  }
+
+  nums.sort();
+  dfs(0, []);
+
+  return subsets;
+}
+
+console.log(subsetsWithDup([1, 2, 2]));