feat: add lc 46, 39, 78

work/1/Medium/Array/46.permutations.py

@@ -0,0 +1,59 @@
+"""
+46. Permutations
+Difficulty: Medium
+https://leetcode.com/problems/permutations/
+
+──────────────────────────────────────────────────
+
+Given an array nums of distinct integers, return all the possible
+permutations. You can return the answer in any order.
+
+
+
+Example 1:
+
+Input: nums = [1,2,3]
+Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
+
+Example 2:
+
+Input: nums = [0,1]
+Output: [[0,1],[1,0]]
+
+Example 3:
+
+Input: nums = [1]
+Output: [[1]]
+
+
+
+Constraints:
+
+        • 1 <= nums.length <= 6
+
+        • -10 <= nums[i] <= 10
+
+        • All the integers of nums are unique.
+"""
+
+
+class Solution:
+    def permute(self, nums: list[int]) -> list[list[int]]:
+        result, path = [], []
+        used = [False] * len(nums)
+
+        def backtrack():
+            if len(path) == len(nums):
+                result.append(path[:])
+                return
+            for i in range(len(nums)):
+                if used[i]:
+                    continue
+                used[i] = True
+                path.append(nums[i])
+                backtrack()
+                path.pop()
+                used[i] = False
+
+        backtrack()
+        return result