46. Permutations

Author: papilo-cloud

Backtracking/permute.py

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+# 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.
+
+
+from typing import List
+class Solution:
+    def permute(self, nums: List[int]) -> List[List[int]]:
+        ans = []
+        chk = [False]*len(nums)
+
+        def dfs(path):
+            if len(nums) == len(path):
+                return ans.append(path.copy())
+            for i, n in enumerate(nums):
+                if chk[i]:
+                    continue
+                chk[i] = True
+                path.append(n)
+                dfs(path)
+                path.pop()
+                chk[i] = False
+        dfs([])
+        return ans