Create 78-Subsets.md

Author: TBXark

78-Subsets.md

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+# 78. Subsets
+
+### 2022-05-10
+
+Given an integer array `nums` of **unique** elements, return *all possible subsets (the power set)*.
+
+The solution set **must not** contain duplicate subsets. Return the solution in **any order**.
+
+ 
+
+**Example 1:**
+
+```
+Input: nums = [1,2,3]
+Output: [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3]]
+```
+
+**Example 2:**
+
+```
+Input: nums = [0]
+Output: [[],[0]]
+```
+
+ 
+
+
+
+# Solution
+
+```swift
+class Solution {
+    func subsets(_ nums: [Int]) -> [[Int]] {
+        var temp = [[Int]]()
+        _subset(nums: nums, context: [], level: 0, store: &temp)
+        return temp
+    }
+    
+    private func _subset(nums: [Int], context: [Int], level: Int, store: inout [[Int]]) {
+        guard nums.count > level else {
+            store.append(context)
+            return
+        }
+        _subset(nums: nums, context: context, level: level + 1, store: &store)
+        var ctx = context
+        ctx.append(nums[level])
+        _subset(nums: nums, context: ctx, level: level + 1, store: &store)
+    }
+}
+```